Image sensing device, image sensing apparatus, a method of manufacturing an image sensing device, and a method of adjusting an image sensing device

ABSTRACT

An image sensing device includes a prism unit, image sensing element, and adjustment mechanism. The prism unit has at least two reflecting surfaces each having a free-form surface shape. The image sensing element converts an image formed on the imaging plane of the prism unit into an electrical signal. The adjustment mechanism has an adjustment member and a receiving portion. The adjustment member can move in a plane parallel to the light-receiving surface of the image sensing element. The receiving portion is arranged on the prism unit and abuts against the adjustment member. The receiving portion finely adjusts a position of the prism unit in a direction perpendicular to the light-receiving surface of the image sensing element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromprior Japanese Patent Applications No. 2003-373595, filed Oct. 31, 2003;No. 2003-373596, filed Oct. 31, 2003; No. 2003-373597, filed Oct. 31,2003; No. 2003-373598, filed Oct. 31, 2003; No. 2003-373599, filed Oct.31, 2003; and No. 2003-373600, filed Oct. 31, 2003, the entire contentsof all of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image sensing device used in adigital camera or a cellular phone with a camera and, more particularly,to an image sensing device which uses a prism having a free-form surfaceas a reflecting surface, an image sensing apparatus using the imagesensing device, and an image sensing position switching method.

2. Description of the Related Art

In recent years, a number of applications for image sensing apparatuseswhich use a coaxial optical system have been filed as image sensingapparatuses used in digital cameras or cellular phones with a camera. Ina coaxial optical system, optical elements such as a lens arerotationally symmetrical with respect to the optical axis (an axis whichconnects the center of the aperture of the image sensing system and thecenter of the image sensing screen) of the optical system. Image sensingapparatuses having a coaxial system are disclosed in, e.g., Jpn. Pat.Appln. KOKAI Publications No. 2001-272587 (reference 1), No. 2002-267928(reference 2), and No. 2002-320122 (reference 3).

Recent digital cameras and cellular phones with a camera are required tobe compact and thin and have high performance. In these devices, if theimage sensing device using a coaxial optical system should be compact,the number of lenses must be decreased. However, when the number oflenses is decreased, aberrations generated in the optical system canhardly be suppressed, resulting in poor image quality. To obtain a highimage quality, the number of lenses must be increased. As a result, theimage sensing device becomes bulky.

As a means for solving these problems, image sensing apparatuses usingan eccentric optical system have been proposed. Image sensingapparatuses using an image sensing optical system using a prism with afree-form surface are disclosed in, e.g., Jpn. Pat. Appln. KOKAIPublications No. 11-326766 (reference 4), No. 2002-196243 (reference 5),and No. 2003-84200 (reference 6).

In this specification, a “free-form surface” means a curved surfacewhich is rotationally asymmetrical with respect to the optical axis ofthe light beam which strikes the surface or the optical axis of thelight beam which exits from the surface and has only one mirror imagesurface along these optical axes.

The techniques described in references 4 to 6 aim at obtaining a compactdevice and a high-quality image by forming an image sensing opticalsystem by using a prism having a free-form surface as a light incidentsurface, light exit surface, or reflecting surface. Especially, inreferences 5 and 6, two prisms are combined. The light incident surface,reflecting surface, and light exit surface of the first prism close tothe object and the light incident surface, two reflecting surfaces, andlight exit surface of the second prism close to the image sensingsurface, i.e., a total of seven surfaces are formed as free-formsurfaces.

The characteristic features of such an optical system are as follows.

(1) The three reflecting surfaces are formed from free-form surfaceshaving a power (refracting power). These reflecting surfaces can obtaina large power and are rarely affected chromatic aberration as comparedto a refractive optical system such as a lens.

(2) The seven optical surfaces can be formed in a compact space. Hence,the optical elements are concentratedly set in the limited space.

(3) To obtain high optical performance, the optical path length of theentire optical system is preferably long to some extent. When theoptical path is bent by using such a prism optical system, the opticalpath length of the optical system can be long, and the entire size canbe small.

For these reasons, a high image quality can be obtained by a compactdevice.

The optical system described in Jpn. Pat. Appln. KOKAI Publication No.7-333505 (reference 7) includes a reflecting mirror, an optical systemby a lens, and a reflecting mirror sequentially from the object side. Ascompared to this system, the optical system described in reference 5 or6 can reduce the width. For this reason, a more compact image sensingdevice can be provided.

When an image sensing device is used in a compact and thin digitalcamera or a cellular phone with a camera, the angle of view of the imagesensing optical system may be set to a wide angle to implement panfocus. In pan focus, an in-focus state is obtained almost throughout theobject distance range by fixed focusing.

Recently, demands for reading a barcode or letters on books or originalsby using a digital camera or a cellular phone with a camera having theimage sensing device are growing. To meet these demands, the pan-focusimage sensing device must have a mechanism suitable formacrophotography. However, references 1 to 6 described above have nodescription of this technique.

In mass-producing such image sensing apparatuses, it is difficult toaccurately form an object image on the image sensing surface of theimage sensing element to read an image due to variations inmanufacturing dimensions of the optical system, variations inmanufacturing dimensions of individual components of the holding frameof the optical system, variations of characteristics, or variations inassembling them.

To solve this problem, focus surface adjustment (to be referred to as fcadjustment hereinafter) must be done for individual image sensingapparatuses such that the position of the light-receiving surface of theimage sensing element and the imaging plane can obtain the mostsatisfactory relationship. However, no fc adjustment mechanism suitablefor such an image sensing device is described in the above prior arts.No means for implementing both the above-described mechanism suitablefor macrophotography and the fc adjustment mechanism is disclosed,either.

BRIEF SUMMARY OF THE INVENTION

The present invention provides an image sensing device capable ofexecuting fc adjustment to correct, at the time of assembly, a shift infocal point caused by manufacturing dimensional errors of each member.The present invention also provides an image sensing apparatus havingthe image sensing device.

An image sensing device according to the present invention comprises aprism unit, image sensing element, adjustment member, and receivingportion. The prism unit receives a light beam from an object and formsan object image on an imaging plane. The prism unit has at least tworeflecting surfaces each having a free-form surface shape. An incidentoptical axis of the light beam input from the object and an exit opticalaxis of the light beam which exits from the prism unit to the imagingplane are arranged substantially in parallel at a predeterminedinterval. The image sensing element is arranged on the imaging plane toconvert the object image formed by the prism unit into an electricalsignal. The adjustment member moves in a plane parallel to thelight-receiving surface of the image sensing element to finely adjust aposition of the prism unit in a direction perpendicular to thelight-receiving surface of the image sensing element. The receivingportion is arranged on the prism unit and abuts against the adjustmentmember to finely adjust the position of the prism unit in the directionperpendicular to the light-receiving surface.

In this specification, a “free-form surface” means a curved surfacewhich is rotationally asymmetrical with respect to the optical axis ofthe light beam which incidents the surface or the optical axis of thelight beam which exits from the surface and has only one mirror imagesurface along these optical axes.

In this case, the prism unit comprises two prisms and aperture member.Each prism has at least one reflecting surface having a free-formsurface shape, a light incident surface having a refracting power, and alight exit surface having a refracting power. An aperture member isarranged between the prisms.

The adjustment member preferably rotates in the plane parallel to thelight-receiving surface of the image sensing element. The adjustmentmember has, at a portion which abuts against the receiving portion, aslant whose position in a direction perpendicular to the light-receivingsurface of the image sensing element changes along a direction in whichthe adjustment member moves. The receiving portion comprises an inclinehaving a shape conforming to the slant of the adjustment member at aportion which abuts against the slant of the adjustment member. Thedevice preferably further comprises a fixing portion to fix theadjustment member at a predetermined position. The image sensing devicealso preferably comprises an eccentric cam or an eccentric pin to finelyadjust a position of the adjustment member.

An adjustment member according to another aspect has a first portion anda second portion. The first portion is a portion which abuts against thereceiving portion of the prism unit. The second portion comes intocontact with an fc adjustment jig to move the adjustment member in adirection parallel to the light-receiving surface of the image sensingelement and is separated from the first portion in a state in which thefirst portion is fixed at a predetermined position with respect to theprism unit.

An image sensing apparatus according to the present invention comprisesthe above-described image sensing device, processing means, andrecording means. The processing means executes predetermined electricalprocessing for the electrical signal obtained by the image sensingelement to obtain image data. The recording means records the image datafrom the processing means on an applied information recording medium.

An image sensing device manufacturing method according to the presentinvention is applied to an image sensing device including a prism unit,image sensing element, and adjustment mechanism. The prism unit receivesa light beam from an object and forms an object image on an imagingplane. The prism unit has at least two reflecting surfaces each having afree-form surface shape. An incident optical axis of the light beaminput from the object and an exit optical axis of the light beam whichexits from the prism unit to the imaging plane are arrangedsubstantially in parallel at a predetermined interval. The image sensingelement is arranged on the imaging plane to convert the object imageformed by the prism unit into an electrical signal.

The adjustment mechanism finely adjusts the position of the prism unitin a direction perpendicular to the light-receiving surface of the imagesensing element. The adjustment mechanism comprises, e.g., an adjustmentmember and a receiving portion. The adjustment member can move in aplane parallel to the light-receiving surface of the image sensingelement. The receiving portion is arranged on the prism unit and abutsagainst the adjustment member. When the adjustment member moves, theposition of the prism unit is finely adjusted in the directionperpendicular to the light-receiving surface. An example of theadjustment member has a first portion and a second portion. The firstportion is a portion which abuts against the receiving portion of theprism unit. The second portion is a portion (e.g., a chucking portion)which comes into contact with an fc adjustment jig to move theadjustment member in a first direction.

The method of manufacturing the image sensing device has steps, such asa step of assembling the prism unit, the image sensing element, and theadjustment mechanism; a step of fixing the first portion of theadjustment member; and a step of separating the second portion of theadjustment member. These steps are executed in this order.

An image sensing device adjustment method according to the presentinvention is applied-to an image sensing device including a prism unit,image sensing element, adjustment member, and receiving portion. Theposition of the prism unit is finely adjusted in a directionperpendicular to the light-receiving surface of the image sensingelement by moving the adjustment member in a plane parallel to thelight-receiving surface of the image sensing element, and the adjustmentmember is fixed such that the state is maintained.

An image sensing device according to another aspect of the presentinvention comprises an optical system, image sensing element, adjustmentmeans, and receiving means. The optical system receives a light beamfrom an object and forms an object image on an imaging plane. Theoptical system has at least two reflecting surfaces each having afree-form surface shape. An incident optical axis of the light beaminput from the object and an exit optical axis of the light beam whichexits from the optical system to the imaging plane are arrangedsubstantially in parallel at a predetermined interval. The image sensingelement is arranged on the imaging plane to convert the object imageformed by the optical system into an electrical signal. The adjustmentmeans can move in a plane parallel to the light-receiving surface of theimage sensing element to finely adjust a position of the optical systemin a direction perpendicular to the light-receiving surface of the imagesensing element. The receiving means is arranged on the optical systemand abuts against the adjustment member to finely adjust the position ofthe optical system in the direction perpendicular to the light-receivingsurface.

The image sensing device having the above arrangement can adjust thefocal plane even when the distance from the imaging plane of the prismunit to the light-receiving surface of the image sensing element changesdue to variations in dimensions of each component of the image sensingdevice or a variation in assembly. For this reason, the image sensingdevice of the present invention can set the focus in an optimum stateeven in, e.g., mass production.

Advantages of the invention will be set forth in the description whichfollows, and in part will be obvious from the description, or may belearned by practice of the invention. Advantages of the invention may berealized and obtained by means of the instrumentalities and combinationsparticularly pointed out hereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention, andtogether with the general description given above and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention.

FIG. 1 is a perspective view of a digital camera having an image sensingdevice of the first embodiment according to the present invention;

FIG. 2 is a sectional view schematically showing the internal structureof the digital camera shown in FIG. 1;

FIG. 3 is a side view of the prism unit of the digital camera shown inFIG. 1;

FIG. 4 is an exploded perspective view of the prism unit shown in FIG.3;

FIG. 5 is a perspective view of the first prism of the prism unit shownin FIG. 3;

FIG. 6 is a perspective view of the second prism of the prism unit shownin FIG. 3;

FIG. 7 is a perspective view of the aperture member of the prism unitshown in FIG. 3;

FIG. 8 is a front view of the aperture member of the prism unit shown inFIG. 3;

FIG. 9 is a rear view of the aperture member of the prism unit shown inFIG. 3;

FIG. 10 is a perspective view of the prism unit shown in FIG. 3;

FIG. 11 is a side view of the first prism and second prism of the prismunit shown in FIG. 3;

FIG. 12 is an exploded perspective view of the image sensing deviceincorporated in the digital camera shown in FIG. 1;

FIG. 13 is a perspective view of the image sensing device shown in FIG.12;

FIG. 14 is a perspective view of the image sensing device in FIG. 13,showing a state in which the case member is detached;

FIG. 15 is a partially cutaway plan view of the image sensing deviceshown in FIG. 13, which is viewed from the side of incidence;

FIG. 16 is a partially cutaway side view of the image sensing deviceshown in FIG. 13, which is viewed from the side of the second prism;

FIG. 17 is a side view showing the first stable posture of the imagesensing device shown in FIG. 13;

FIG. 18 is a side view showing the second stable posture of the imagesensing device shown in FIG. 13;

FIG. 19 is a sectional view of the image sensing device shown in FIG.17;

FIG. 20 is a sectional view of the image sensing device shown in FIG.18;

FIG. 21 is an exploded perspective view showing an image sensing deviceof the second embodiment according to the present invention;

FIG. 22 is a partially cutaway plan view of the image sensing deviceshown in FIG. 21, which is viewed from the side of incidence;

FIG. 23 is a partially cutaway side view of the image sensing deviceshown in FIG. 21, which is viewed from the side of the second prism;

FIG. 24 is a sectional view of the image sensing device shown in FIG.21, which is taken along a direction in which the prisms are arranged;

FIG. 25 is a sectional view of the image sensing device in which thefine adjustment mechanism is moved from the state shown in FIG. 24 tothe side of the second prism;

FIG. 26 is a sectional view of the image sensing device in which thefine adjustment mechanism is moved from the state shown in FIG. 24 tothe side of the first prism;

FIG. 27 is an exploded perspective view showing an image sensing deviceof the third embodiment according to the present invention;

FIG. 28 is a perspective view of the image sensing device shown in FIG.27;

FIG. 29 is a side view of the image sensing device shown in FIG. 28;

FIG. 30 is a sectional view of the image sensing device shown in FIG.29;

FIG. 31 is a sectional view of the image sensing device shown in FIG.29;

FIG. 32 is a perspective view showing an image sensing device of thefourth embodiment according to the present invention;

FIG. 33 is an exploded perspective view of an image sensing device ofthe fifth embodiment according to the present invention;

FIG. 34 is a perspective view of the image sensing device shown in FIG.33;

FIG. 35 is a perspective view of the image sensing device shown in FIG.34, showing a state in which the case member and prism unit aredetached;

FIG. 36 is a partially cutaway plan view of the image sensing deviceshown in FIG. 34, which is viewed from the side of incidence;

FIG. 37 is a partially cutaway side view of the image sensing deviceshown in FIG. 34, which is viewed from the side of the second prism;

FIG. 38 is a side view of the image sensing device shown in FIG. 34 whenthe switching mechanism is at the first setting position;

FIG. 39 is a sectional view of the image sensing device shown in FIG.38;

FIG. 40 is a side view of the image sensing device shown in FIG. 34 whenthe switching mechanism is at the second setting position;

FIG. 41 is a sectional view of the image sensing device shown in FIG.40;

FIG. 42 is an exploded perspective view showing an image sensing deviceof the sixth embodiment according to the present invention;

FIG. 43 is a partially cutaway side view of the image sensing deviceshown in FIG. 42 which is viewed from the side of the second prism;

FIG. 44 is a side view of the image sensing device shown in FIG. 42 whenthe switching mechanism is at the first setting position;

FIG. 45 is a sectional view of the image sensing device shown in FIG.44;

FIG. 46 is a side view of the image sensing device shown in FIG. 42 whenthe switching mechanism is at the second setting position;

FIG. 47 is a sectional view of the image sensing device shown in FIG.46;

FIG. 48 is a perspective view showing the adjustment mechanism andsupport pin of an image sensing device of the seventh embodimentaccording to the present invention;

FIG. 49 is a side view schematically showing the positional relationshipbetween the switching mechanism, fine adjustment mechanism, and supportpin shown in FIG. 48;

FIG. 50 is a perspective view of an image sensing device of the eighthembodiment according to the present invention;

FIG. 51 is an exploded perspective view of the image sensing deviceshown in FIG. 50;

FIG. 52 is a perspective view of the image sensing device shown in FIG.50 and a jig to execute fc adjustment;

FIG. 53 is a plan view of an image sensing device of the ninthembodiment according to the present invention;

FIG. 54 is a side view of the image sensing device shown in FIG. 53 whenthe switching mechanism is at the first setting position;

FIG. 55 is a side view of the prism unit of the image sensing deviceshown in FIG. 53;

FIG. 56 is a side view of the image sensing device shown in FIG. 53 whenthe switching mechanism is at the second setting position;

FIG. 57 is a perspective view of an image sensing device of the 10thembodiment according to the present invention;

FIG. 58 is a perspective view of an image sensing device of the 11thembodiment according to the present invention;

FIG. 59 is a partially sectional side view of an image sensing device ofthe 12th embodiment according to the present invention;

FIG. 60 is a partially sectional plan view of the image sensing deviceshown in FIG. 59;

FIG. 61 is a perspective view of an image sensing device of the 13thembodiment according to the present invention;

FIG. 62 is a plan view of the image sensing device shown in FIG. 61;

FIG. 63 is a front view of the image sensing device shown in FIG. 61;

FIG. 64 is a sectional view of the image sensing device taken along aline F64-F64 in FIG. 63;

FIG. 65 is a plan view showing another example of the fc adjustment jigtogether with part of the image sensing device;

FIG. 66 is a perspective view of an image sensing device of the 14thembodiment according to the present invention;

FIG. 67 is a sectional view of the image sensing device shown in FIG.66;

FIG. 68 is an exploded perspective view of the image sensing deviceshown in FIG. 66;

FIG. 69 is a plan view of the image sensing device shown in FIG. 66;

FIG. 70A is a front view of the image sensing device shown in FIG. 66when the switching mechanism is at the first setting position;

FIG. 70B is a front view of the image sensing device shown in FIG. 66when the switching mechanism is at the second setting position;

FIG. 71 is a perspective view of an image sensing device of the 15thembodiment according to the present invention;

FIG. 72 is a sectional view of the image sensing device shown in FIG.71;

FIG. 73A is a front view of the image sensing device shown in FIG. 71when the switching mechanism is at the first setting position;

FIG. 73B is a front view of the image sensing device shown in FIG. 71when the switching mechanism is at the second setting position;

FIG. 74 is a perspective view of an image sensing device of the 16thembodiment according to the present invention;

FIG. 75A is a front view of the image sensing device shown in FIG. 74when the switching mechanism is at the first setting position;

FIG. 75B is a front view of the image sensing device shown in FIG. 74when the switching mechanism is at the second setting position;

FIG. 76 is a front view of the switching mechanism of an image sensingdevice of the 17th embodiment according to the present invention;

FIG. 77 is a perspective view showing a cellular phone with a camera asanother example of the image sensing apparatus according to the presentinvention;

FIG. 78 is a sectional view schematically showing another example of theprism optical system;

FIG. 79 is a sectional view schematically showing still another exampleof the prism optical system;

FIG. 80 is a sectional view schematically showing still another exampleof the prism optical system;

FIG. 81 is a perspective view showing a digital camera as still anotherexample of the image sensing apparatus according to the presentinvention;

FIG. 82 is a sectional view schematically showing the internal structureof the digital camera shown in FIG. 81;

FIG. 83 is a perspective view showing a cellular phone with a camera asstill another example of the image sensing apparatus having the imagesensing device according to the present invention;

FIG. 84 is a sectional view schematically showing still another exampleof the prism optical system;

FIG. 85 is a sectional view schematically showing still another exampleof the prism optical system; and

FIG. 86 is a sectional view schematically showing still another exampleof the prism optical system.

DETAILED DESCRIPTION OF THE INVENTION

An image sensing apparatus according to the first embodiment of thepresent invention will be described with reference to FIGS. 1 to 20 byexemplifying a digital camera. As shown in FIG. 1, a digital camera 1has a release button 20, electronic flash 21, finder optical system 22,image sensing optical system 23, and image monitor 24 (FIG. 2), whichare arranged on the outer surface of a housing 2. As shown in FIG. 2,the housing 2 incorporates an image sensing device 10 which forms themain part of the image sensing optical system 23, an image processingcircuit 25 serving as a proccessing means, and a recording unit 26serving as a recording means. The image processing circuit 25 has afunction of executing predetermined electrical processing for anelectrical signal obtained by the image sensing device 10 to obtainimage data. The recording unit 26 functions as a recording means forrecording image data from the image processing circuit 25 on an appliedrecording medium. In this case, the “applied recording medium” is aflash memory incorporated in the digital camera 1 or an externallydetachable memory card.

The image sensing device 10 includes a prism unit 30 as an example of aneccentric optical system in which an incident optical axis λi and exitoptical axis λo are arranged almost in parallel at a predeterminedinterval, and an image sensing element 12 mounted on a board 11. FIGS. 3to 11 show an example of the prism unit 30. The prism unit 30 has afirst prism 41, second prism 42, and aperture member 43. The imagesensing element 12 is an element such as a CCD which converts light intoan electrical signal and is arranged on the exit side of the prism unit30. A cover glass 12 a is attached to the light-receiving surface of theimage sensing element 12. In place of the cover glass 12 a, an opticalmember such as a polarizing filter may be attached.

As shown in FIG. 3, the first prism 41 is an eccentric prism includingan incident surface 51, rotationally asymmetric reflecting surface 52,and exit surface 53. As shown in FIG. 5, the exit surface 53 of thefirst prism 41 has a plane portion 53 b formed flat outside an effectivediameter portion 53 a of the optical path. The plane portion 53 b hastwo positioning portions 53 c and 53 d formed into a cylindrical shapeand three projecting portions 53 e, 53 f, and 53 g formed into ahemispherical shape. The positioning portions 53 c and 53 d are arrangedoutside the effective diameter portion 53 a. In this embodiment, asshown in FIGS. 4 and 5, the positioning portions 53 c and 53 d arearranged symmetrically with respect to a plane A1 which crosses theeffective diameter portion 53 a along the incident optical axis λi.

The projecting portions 53 e and 53 g are arranged outside thepositioning portions 53 c and 53 d which sandwich the effective diameterportion 53 a with respect to the plane A1. Hence, the distance from thecentral position of the effective diameter portion 53 a to theprojecting portions 53 e and 53 g is longer than the distance to thepositioning portions 53 c and 53 d. The projecting portion 53 f isarranged outside the effective diameter portion 53 a and inside thepositioning portions 53 c and 53 d with respect to the plane A1. In thisembodiment, the plane A1 is arranged at a position that crosses theplane portion 53 b. As described above, of the three projectingportions, at least two projecting portions are arranged at (farther)positions separated from the central position of the effective diameterportion 53 a by a distance longer than the distance to the positioningportions.

As shown in FIG. 3, the second prism 42 is an eccentric prism includingan incident surface 61, reflecting surface 62, reflecting surface 63,and exit surface 64. At least one of the reflecting surfaces 62 and 63is rotationally asymmetrical. As shown in FIG. 6, the incident surface61 of the second prism 42 has a plane portion 61 b formed flat outsidean effective diameter portion 61 a of the optical path. The planeportion 61 b has two positioning portions 61 c and 61 d formed into acylindrical shape and three projecting portions 61 e, 61 f, and 61 gformed into a hemispherical shape. The positioning portions 61 c and 61d are arranged outside the effective diameter portion 61 a. Thepositioning portions 61 c and 61 d are arranged symmetrically withrespect to a plane A2 which crosses the effective diameter portion 61 aalong the exit optical axis λo.

The projecting portions 61 e and 61 g are arranged outside thepositioning portions 61 c and 61 d which sandwich the effective diameterportion 61 a with respect to the plane A2. The projecting portion 61 fis arranged outside the effective diameter portion 61 a and inside thepositioning portions 61 c and 61 d with respect to the plane A2. Theprojecting portions 61 e, 61 f, and 61 g are arranged on the incidentsurface 61 to be asymmetrical with respect to the plane A2.

As shown in FIGS. 7 to 9, the aperture member 43 has an opening portion62 a which is formed in accordance with the effective diameter of theoptical planes of action of the two prisms, i.e., the first prism 41 andsecond prism 42. The aperture member 43 also functions as a holdingmember which maintains the relative positional relationship between thefirst prism 41 and the second prism 42. The aperture member 43 has, onboth surfaces near the opening portion 62 a, plane portions 62 b and 62c formed into a planar shape outside the opening portion 62 a.

Positioning/holding portions 62 d, 62 e, 62 f, and 62 g are formed inthe plane portions 62 b and 62 c. The positioning/holding portions 62 dto 62 g are formed at positions corresponding to the positioningportions 53 c, 53 d, 61 c, and 61 d of the first prism 41 and secondprism 42 as through holes which can fit on the positioning portions 53c, 53 d, 61 c, and 61 d, respectively. A thickness H of the aperturemember 43 is designed to, e.g., H=1.12 mm. A length t of eachpositioning portion of the first prism 41 and second prism 42 isdesigned to, e.g., t=0.55 mm. In this case, t/H=0.49.

In the prism unit 30 having the above-described structure, thepositioning portion 53 c of the first prism 41 is fitted in thepositioning/holding portion 62 d from the side of the plane portion 62 bof the aperture member 43, and the positioning portion 53 d is fitted inthe positioning/holding portion 62 e. Accordingly, the position of thefirst prism 41 with respect to the aperture member 43 is determined. Atthis time, the projecting portions 53 e, 53 f, and 53 g of the firstprism 41 abut against the plane portion 62 b of the aperture member 43so that the tilt of the first prism 41 with respect to the aperturemember 43 is determined.

Similarly, the positioning portion 61 c of the second prism 42 is fittedin the positioning/holding portion 62 f from the side of the planeportion 62 c of the aperture member 43, and the positioning portion 61 dis fitted in the positioning/holding portion 62 g. Accordingly, theposition of the second prism with respect to the aperture member 43 isdetermined. At this time, the projecting portions 61 e, 61 f, and 61 gof the second prism 42 abut against the plane portion 62 c of theaperture member 43 so that the tilt of the second prism 42 with respectto the aperture member 43 is determined.

In this way, the first prism 41 and second prism 42 are held on bothsides of the aperture member 43, as shown in FIG. 10. As shown in FIG.11, one set of holding portions 62 d and 62 e and the other set ofpositioning/holding portions 62 f and 62 g are arranged at differentpositions so that the line which passes through the center of gravity ofthe first prism 41 and the line which passes the center of gravity ofthe second prism 42 are not arranged on a straight line on the aperturemember 43.

In the state shown in FIG. 10, if the tilts of the first prism 41 andsecond prism 42 with respect to the aperture member 43 need to beadjusted, the projecting portions 53 e, 53 f, and 53 g of the firstprism 41 and the projecting portions 61 e, 61 f, and 61 g of the secondprism 42 are ground by a predetermined amount in accordance with thedirections and degrees of tilts. Accordingly, the tilts of the firstprism 41 and second prism 42 can easily be adjusted.

As described above, the prism unit 30 of this embodiment receives alight beam from an object and forms an object image on an imaging plane45. The prism unit 30 has at least two reflecting surfaces, in thisembodiment three reflecting surfaces 52, 62, and 63 having free-formsurface shapes. The incident optical axis λi of the light beam whichenters from the object surface and the exit optical axis λo of the lightbeam which exits from the prism unit 30 to the imaging plane 45 areformed by the prism optical systems which are arranged almost inparallel while being separated by a predetermined distance. With thisstructure, the prism unit 30 of this embodiment receives a light beamfrom an object and forms an object image on the imaging plane 45.

A mechanism of the image sensing device 10, which moves theabove-described prism unit 30 in a direction crossing thelight-receiving surface of the image sensing element 12 and, morepreferably, in a direction perpendicular to the light-receiving surfaceof the image sensing element 12, will be described next with referenceto FIGS. 12 to 20. For the descriptive convenience, the directionperpendicular to the light-receiving surface of the image sensingelement 12 will be defined as an X direction, the direction in which thefirst prism 41 and second prism 42 are arranged will be defined as a Ydirection, and the direction perpendicular to the Y and X directionswill be defined as a Z direction in the drawings. As shown in FIG. 12,the image sensing device 10 comprises a fixing member 13, case member14, lever members 15, switching member 16, and connection spring 17 inaddition to the above-described prism unit 30 and image sensing element12.

The fixing member 13 is arranged between the prism unit 30 and the imagesensing element 12. The fixing member 13 has a window 13 a at thecentral portion. The fixing member 13 locates and holds thelight-receiving surface of the image sensing element 12 on the exitoptical axis λo such that the light beam which exits from the secondprism 42 of the prism unit 30 passes through the window 13 a and formsan image on the light-receiving surface of the image sensing element 12.First abutment portions 13 b which abut against part of the prism unit30 are formed on the fixing member 13 on the side facing the prism unit30.

As shown in FIG. 13, the case member 14 covers the prism unit 30 and isfixed to the fixing member 13. The case member 14 has an incident window14 a at a portion through which the light beam that should enter thefirst prism 41 of the prism unit 30 passes. A protective glass 14 b isfitted in the incident window 14 a. As the protective glass 14 b,IR-blocking glass is preferably used. Second abutment portions 14 cwhich abut against part of the prism unit 30 are formed inside the casemember 14 on the side facing the prism unit 30.

As shown in FIG. 14, the aperture member 43 of the prism unit 30 hasguide plates 31. The guide plates 31 are arranged in parallel to theplanes A1 and A2 along which the incident optical axis λi and exitoptical axis λo pass so that the first prism 41 and second prism 42 aresandwiched from both sides. The guide plates 31 may be either integratedwith the aperture member 43 or attached as separate components. As shownin FIG. 15, the guide plates 31 are in slidable contact with the innersurfaces of the case member 14. The guide plates 31 thus prevent theprism unit 30 from shifting in the widthwise direction (Z direction)with respect to the Y direction in which the first prism 41 and secondprism 42 are arranged and the X direction perpendicular to thelight-receiving surface of the image sensing element 12.

The guide plates 31 have bosses 31 a which are formed into a cylindricalshape extending in the direction along the plane portions 62 b and 62 cof the aperture member 43. Support pins 32 which rotationally connectthe prism unit 30 to the lever members 15 are attached to the bosses 31a. Hence, slits 14 d which receive the bosses 31 a and support pins 32are formed in the case member 14.

Projecting portions bulging toward the fixing member 13 are formed atfour corners of the guide plates 31 facing the fixing member 13. Thedistal ends of the projecting portions form third abutment portions 31 bwhich abut against the first abutment portions 13 b to locate the prismunit 30 at a first position P1 closest to the image sensing element 12.The first abutment portions 13 b and third abutment portions 31 b formplanes which coincide with each other so that the prism unit 30 islocated at the first position P1.

Convex portions bulging toward the second abutment portions 14 c areformed at four corners of the guide plates 31 facing the case member 14.The distal ends of the projecting portions form fourth abutment portions31 c which abut against the second abutment portions 14 c to locate theprism unit 30 at a second position P2 farthest from the image sensingelement 12. The second abutment portions 14 c and fourth abutmentportions 31 c form planes which coincide with each other so that theprism unit 30 is located at the second position P2.

In this embodiment, the third abutment portions 31 b and fourth abutmentportions 31 c are described as planes formed by the distal ends of theprojecting portions. However, the third abutment portions 31 b andfourth abutment portions 31 c may have shapes that match the firstabutment portions 13 b and second abutment portions 14 c, respectively.Alternatively, the third abutment portions 31 b and fourth abutmentportions 31 c may be formed on planes, and the first abutment portions13 b and second abutment portions 14 c may be formed as projectingportions whose distal ends are arranged on planes which coincide withthe third abutment portions 31 b and fourth abutment portions 31 c.

The lever members 15 are arranged on both sides of the case member 14along the Y direction in which the first prism 41 and second prism 42are arranged. Proximal portions 15 a of the lever members 15 arerotationally supported by rotating shafts R1 which are attached atcorners of the case member 14 on the second prism unit side. Therotating shafts R1 are arranged in parallel to the direction in whichthe bosses 31 a and support pins 32 extend. The lever members 15 rotateon the rotating shafts R1 to move the prism unit 30 connected throughthe support pins 32 in the direction crossing the light-receivingsurface of the image sensing element 12 and, more preferably, in thedirection perpendicular to the light-receiving surface of the imagesensing element 12. That is, the lever members 15 function as supportmembers which movably support the prism unit 30 within a predeterminedmovable range along the direction crossing the light-receiving surfaceof the image sensing element 12.

Proximal portions 16 a of the switching member 16 are rotationallysupported by the rotating shafts R1 to be coaxial with the proximalportions 15 a of the lever members 15. Distal ends 15 b of the levermembers 15 and distal ends 16 b of the switching member 16, which areseparated from the rotating shafts R1 in the radial direction, areconnected by connection springs 17. The distal ends 16 b of theswitching member 16 are located closer to the rotating shafts R1 thanthe distal ends 15 b of the lever members 15. With this structure, thedistal ends 15 b of the lever members 15 and the distal ends 16 b of theswitching member 16 can pass each other without interfering with theconnection springs 17 and spring brackets 18 a and 18 b whichrotationally support the connection springs 17 at the distal ends 15 band 16 b.

The connection springs 17 urge the distal ends 15 b of the lever members15 and the distal ends 16 b of the switching member 16 in directions inwhich they separate. Hence, as shown in FIG. 17, when the distal ends 16b of the switching member 16 pivot to positions farther from the imagesensing element 12 and fixing member 13 than the distal ends 15 b of thelever members 15, a first stable posture T1 is obtained so that thelever members 15 maintain a state in which they are kept urged to becloser to the fixing member 13. As shown in FIG. 18, when the distalends 16 b of the switching member 16 pivot to positions closer to theimage sensing element 12 and fixing member 13 than the distal ends 15 bof the lever members 15, a second stable posture T2 is obtained so thatthe lever members 15 maintain a state in which they are kept urged to beseparated from the image sensing element 12 and fixing member 13.

The prism unit 30 is connected to the lever members 15 through thesupport pins 32. For this reason, as the lever members 15 pivot, theprism unit 30 is also moved in the X direction. In the first stableposture T1, the prism unit 30 is urged toward the fixing member 13, asshown in FIG. 19. Accordingly, the third abutment portions 31 b abutagainst the first abutment portions 13 b so that the prism unit 30 islocated at the first position P1 closest to the image sensing element 12within the movable range. In the second stable posture T2, the prismunit 30 is urged toward the case member 14, as shown in FIG. 20.Accordingly, the fourth abutment portions 31 c abut against the secondabutment portions 14 c so that the prism unit 30 is located at thesecond position P2 farthest from the image sensing element 12 within themovable range.

As described above, the switching member 16 and connection springs 17function as a switching mechanism which takes the first stable postureT1 or second stable posture T2 in synchronism with the lever members 15serving as support members to move the prism unit 30 to the firstposition P1 or second position P2 and selectively locate it.

In the image sensing device 10, to switch the focal point between thefirst position P1 and the second position P2, the third abutmentportions 31 b are caused to abut against the first abutment portions 13b to locate the prism unit 30 at the first position P1, and the fourthabutment portions 31 c are caused to abut against the second abutmentportions 14 c to locate the prism unit 30 at the second position P2. Nospecial mechanism that translates the prism unit 30 without any shift ofthe optical axis is necessary. Hence, the structure of the image sensingdevice 10 can be simplified.

The connection springs 17 urge the prism unit 30 toward the fixingmember 13 at the first position P1 and toward the case member 14 at thesecond position P2. Hence, the prism unit 30 is reliably maintained atthe first position P1 or second position P2 without any play.

The third abutment portions and fourth abutment portions are formed bythe distal ends of the projecting portions. Hence, the positioning errorof the prism unit 30 within the manufacturing tolerances, which occursin mass production of the image sensing device 10, can easily becorrected by adjusting the heights of the distal ends of the projectingportions.

As shown in FIG. 2, in this embodiment, the first position P1 is, e.g.,the standard image sensing position, and the second position P2 is,e.g., the macro image sensing position. The switching member 16interlocks with a manual operation switching member 95 which is exposedfrom the housing 2 of the digital camera 1 shown in FIG. 1. When themanual operation switching member 95 is operated, the switching member16 is switched between the first stable posture T1 and the second stableposture T2. Hence, when the manual operation switching member 95 isoperated, the prism unit 30 is selectively switched between the firstposition P1 and the second position P2 so that two focus positions canbe set. Instead of manually operating the switching member 16, it may bemotor-driven by using an actuator such as an electric motor.

In this embodiment, the third abutment portions 31 b and fourth abutmentportions 31 c are formed on the guide plates 31 arranged on the aperturemember 43. These abutment portions may be formed on the aperture member43, on part of the first prism 41 and second prism 42, or separately onthe aperture member 43, first prism 41, and second prism 42. Instead ofarranging the case member 14, a bracket having second abutment portionswhich abut against the fourth abutment portions 31 c of the prism unit30 at the second position P2 may be extended from the fixing member 13.

An image sensing device 10 a according to the second embodiment of thepresent invention will be described next with reference to FIGS. 21 to26. The image sensing device 10 a of this embodiment is different fromthe image sensing device 10 of the first embodiment in that the devicefurther comprises a fine adjustment mechanism 70. Components other thanthe fine adjustment mechanism 70 are the same as in the firstembodiment. The same reference numerals as in the first embodimentdenote constituent elements having the same functions in the secondembodiment, and a description thereof will be omitted.

As shown in FIG. 21, the fine adjustment mechanism 70 is mounted betweena fixing member 13 and a prism unit 30. As shown in FIGS. 24 to 26, thefine adjustment mechanism 70 is movable in the Y direction in which afirst prism 41 and a second prism 42 are arranged. A guide portion 13 ewhich overhangs on the side of the first prism 41 along the Y directionis formed on the fixing member 13. A distal end portion 71 of the fineadjustment mechanism 70 on the side of the first prism 41 is insertedbetween the guide portion 13 e and a board 11. A proximal portion 72 ofthe fine adjustment mechanism 70 on the side of the second prism 42 isexposed outside from a case member 14, as shown in FIGS. 22 to 26.

The fine adjustment mechanism 70 has adjustment portions 73 extendingalong the Y direction. As shown in FIGS. 22 and 23, the adjustmentportions 73 are arranged on both sides of a window 13 a. The adjustmentportions 73 sandwich the prism unit 30 at portions close to the fixingmember 13 and extend inside the case member 14. As shown in FIG. 21, theadjustment portions 73 have slants 73 a at positions corresponding tothird abutment portions arranged at four corners of guide plates 31 onthe side of the fixing member 13. First abutment portions 73 b areformed on the slants 73 a. The slants 73 a have the same gradient in themoving direction of the fine adjustment mechanism 70.

The image sensing device 10 a having the fine adjustment mechanism 70with the above-described structure causes third abutment portions 31 barranged on the prism unit 30 to abut against the first abutmentportions 73 b arranged on the fine adjustment mechanism 70 in a firststable posture T1 in which the prism unit 30 is located at a firstposition P1, as shown in FIGS. 24 to 26. In this state, when theadjustment mechanism is moved from the state shown in FIG. 24 to thestate shown in FIG. 25 or from the state shown in FIG. 24 to the stateshown in FIG. 26, displacement along the X direction perpendicular tothe light-receiving surface of an image sensing element 12 occurs by anamount (distance) corresponding to the gradient of the slants 73 a.

In this embodiment, the slants 73 a tilt to the side of the first prism41. When the adjustment mechanism is moved from the state shown in FIG.24 to the state shown in FIG. 25, the prism unit 30 is displaced in adirection to approach the image sensing element 12. When the fineadjustment mechanism 70 is moved from the state shown in FIG. 24 to thestate shown in FIG. 26, the prism unit 30 is displaced in a direction tobe separated from the image sensing element 12.

As described above, in the image sensing device 10 a having the fineadjustment mechanism 70, adjustment of the position of the prism unit30, i.e., fine adjustment (fc adjustment) of the focal plane can be doneat the first position P1 at which the third abutment portions 31 b ofthe prism unit 30 abut against the first abutment portions 73 b of thefine adjustment mechanism 70. After the fc adjustment, the fineadjustment mechanism 70 is fixed by an adhesive or laser melting betweenthe distal end portion 71 and the guide portion 13 e and between theproximal portion 72 and the fixing member 13 or case member 14.

In the first and second embodiments, four third abutment portions 31 band four fourth abutment portions 31 c are formed. However, when atleast three abutment portions are formed, the posture of the prism unit30 can be set to a desired angle with respect to the light-receivingsurface of the image sensing element. In the second embodiment, thenumber of slants 73 a of the fine adjustment mechanism 70 correspondingto the third abutment portions 31 b can also be at least three.

An image sensing device 10 b according to the third embodiment of thepresent invention will be described next with reference to FIGS. 27 to31. The image sensing device 10 b has a mechanism which displaces aprism unit 30 in a direction crossing the light-receiving surface of animage sensing element 12 and, more preferably, in a directionperpendicular to the light-receiving surface of the image sensingelement 12. For the descriptive convenience, the direction perpendicularto the light-receiving surface of the image sensing element 12 will bedefined as an X direction, the direction in which a first prism 41 and asecond prism 42 are arranged will be defined as a Y direction, and thewidthwise direction of the prism unit 30, which is perpendicular to theY and X directions, will be defined as a Z direction in the drawings. Asshown in FIG. 27, the image sensing device 10 b comprises a fixingmember 513, case member 514, pivot support portion 515, and adjustmentmechanism 516 in addition to the above-described prism unit 30 and imagesensing element 12.

The fixing member 513 is arranged between the prism unit 30 and a board11. The fixing member 513 has a window 513 a at the central portion. Thefixing member 513 locates the light-receiving surface of the imagesensing element 12 on an exit optical axis λo such that a light beamwhich exits from the second prism of the prism unit 30 passes throughthe window 513 a and forms an image on the light-receiving surface ofthe image sensing element 12.

The case member 514 has a box shape which covers the prism unit 30except its surface on the side of the fixing member 513. The prism unit30 is fixed in the case member 514. The case member 514 has an incidentwindow 514 a at a portion through which the light beam that should enterthe first prism 41 of the prism unit 30 passes. A protective glass 514 bis fitted in the incident window 514 a. As the protective glass 514 b,IR-blocking glass is preferably used.

As shown in FIG. 27, the prism unit 30 comprises holding plates 531. Theholding plates 531 are arranged in parallel to an X-Y plane along whichan incident optical axis λi and the exit optical axis λo pass so thatthe first prism 41 and second prism 42 are sandwiched from both sides inthe widthwise direction (Z direction). The holding plates 531 may beeither integrated with an aperture member 43 or attached as separatecomponents. When the prism unit 30 has the holding plates 531, thecontact area to the case member 514 increases. Hence, the prism unit 30can more reliably be fixed to the case member 514.

The pivot support portion 515 comprises unit-side plates 515 a,element-side plates 515 b, shaft 515 c, and helical torsion spring 517.The unit-side plates 515 a are fixed to end portions 514 c of the casemember 514 on the side of the first prism 41. The unit-side plates 515 ahave through holes 515 d in a direction perpendicular to the X-Y planealong which the incident optical axis λi and exit optical axis λo pass.The element-side plates 515 b are fixed to end portions 513 b of thefixing member 513 on the side of the first prism 41. The element-sideplates 515 b are arranged to sandwich the unit-side plates 515 a in thewidthwise direction (Z direction) of the prism unit 30. The element-sideplates 515 b have through holes 515 e at positions overlapping thethrough holes 515 d in the unit-side plates 515 a.

The shaft 515 c is inserted to the helical torsion spring 517 and thethrough holes 515 d and 515 e in the direction perpendicular to the X-Yplane along which the incident optical axis λi and exit optical axis λopass. Accordingly, as shown in FIG. 27, the case member 514 whichincorporates the prism unit 30 is supported to rotate on the shaft 515 cwhose pivot center line B is arranged in the direction perpendicular tothe X-Y plane along which the incident optical axis λi and exit opticalaxis λo pass. In other words, the prism unit 30 rotates in a directionin which the prism unit 30 approaches or separates from thelight-receiving surface of the image sensing element 12 about the pivotcenter line B arranged in the direction parallel to the light-receivingsurface of the image sensing element 12 and perpendicular to thedirection in which the incident optical axis λi and exit optical axis λoare arranged, i.e., in the direction perpendicular to the X-Y planealong which the incident optical axis λi and exit optical axis λo pass.

One winding end 517 a of the helical torsion spring 517 is locked to aunit-side spring bracket portion 514 d which projects from the casemember 514 in the widthwise direction (Z direction) of the prism unit30. The other winding end 517 b of the helical torsion spring 517 pivotsin a direction to compress the helical torsion spring 517 against theelasticity and is locked to an element-side spring bracket portion 513 cwhich projects from the fixing member 513 in the widthwise direction (Zdirection) of the prism unit 30, as shown in FIG. 28. Hence, the prismunit 30 and image sensing element 12 are urged in a direction in whichthey approach each other. In this embodiment, the prism unit 30 andimage sensing element 12 are urged by using the helical torsion spring517 in the direction in which they approach each other. Any other urgingmember than the helical torsion spring 517 may be used.

The adjustment mechanism 516 comprises an adjustment piece 516 a and anadjustment screw 516 b. The adjustment piece 516 a is arranged at an endportion 514 e of the case member 514 on the side of the second prism 42.The adjustment screw 516 b is threadably inserted to a female screw 516c extending through the adjustment piece 516 a toward the fixing member513.

As shown in FIG. 29, in the image sensing device 10 b having theabove-described arrangement, along the light-receiving surface of theimage sensing element 12, the pivot support portion 515 is arranged at aposition farther from the aperture member 43 of the prism unit 30 thanthe first prism 41. In addition, the adjustment mechanism 516 isarranged at a position farther from the aperture member 43 than thesecond prism 42. The length of the light-receiving surface of the imagesensing element 12 from the pivot center line B of the pivot supportportion 515 in the radial direction of rotation is smaller than thedistance from the pivot center line B to the exit optical axis λo, asshown in FIG. 30.

Hence, as shown in FIG. 31, the angular displacement between the exitoptical axis λo and the light-receiving surface of the image sensingelement 12 generated by causing the prism unit 30 to rotate on the pivotsupport portion 515 by using the adjustment mechanism 516 is muchsmaller than the displacement in distance between the second prism 42and the light-receiving surface of the image sensing element 12. Thatis, when the prism unit 30 is caused to rotate on the pivot center lineB of the pivot support portion 515 together with the case member 514 byusing the adjustment mechanism 516 to adjust the shift between thelight-receiving surface of the image sensing element 12 and the imagingplane (focal plane) on which the prism unit 30 forms an object image,the angular displacement generated on the imaging plane with respect tothe light-receiving surface of the image sensing element 12 falls withinthe allowable range.

When the light-receiving surface of the image sensing element 12 has arectangular shape, the long sides of the light-receiving surface arearranged in parallel to the pivot center line B of the pivot supportportion. When the image sensing element 12 is thus arranged, the angulardisplacement of the imaging plane with respect to the light-receivingsurface, which is generated when the prism unit 30 rotates on the pivotcenter line B, can be decreased. Hence, the influence of so-called localdefocus in which an in-focus state is obtained at the central portion ofthe screen while an out-of-focus state is generated at the peripheralportion can be reduced.

An image sensing device 10 c according to the fourth embodiment of thepresent invention will be described with reference to FIG. 32. The samereference numerals as in the image sensing device 10 b of the thirdembodiment denote components having the same functions in the fourthembodiment, and a description thereof will be omitted.

The image sensing device 10 c shown in FIG. 32 is different from theimage sensing device 10 b of the third embodiment shown in FIG. 28 inthe structure of a pivot support portion 515. The pivot support portion515 of this embodiment comprises a unit-side plate 515 f and anelement-side plate 515 g. The unit-side plate 515 f is arranged at anend portion 514 c of a case member 514 on the side of a first prism 41near a fixing member 513. The unit-side plate 515 f extends in adirection separating from a prism unit 30 along the light-receivingsurface of an image sensing element 12. The element-side plate 515 g isarranged at an end portion 513 b of the fixing member 513 on the side ofthe first prism 41 along the fixing member 513. The element-side plate515 g is bonded and fixed while overlapping the unit-side plate 515 f.

In this case, a step 518 is formed at the boundary between theelement-side plate 515 g and the fixing member 513 such that a small gapC is formed between the fixing member 513 and the case member 514. Thestep 518 may be formed on the side of the case member 514. With thisstructure, any shift of an overlap portion 515 h between the unit-sideplate 515 f and the element-side plate 515 g in each product can beprevented. The step 518 is formed along a direction perpendicular to theX-Y plane along which an incident optical axis λi and exit optical axisλo of the prism unit 30 pass.

When the prism unit 30 is moved in the direction perpendicular to thelight-receiving surface of the image sensing element 12 together withthe case member 514 by using an adjustment mechanism 516, a pivot centerline B on which the prism unit 30 rotates is arranged near the step 518along the direction perpendicular to the X-Y plane along which theincident optical axis λi and exit optical axis λo of the prism unit 30pass. That is, the prism unit 30 rotates on the pivot center line B ofthe pivot support portion 515.

In the fourth embodiment, in the pivot support portion 515, theunit-side plate 515 f and element-side plate 515 g are bonded and fixedwhile overlapping each other. In this case, the pivot support portion515 need only be formed such that the pivot center line B is arrangedalong the direction perpendicular to the X-Y plane along which theincident optical axis λi and exit optical axis λo of the prism unit 30pass. Hence, the structure from the end portion 513 b of the fixingmember 513 to the end portion 514 c of the case member 514, includingthe pivot support portion 515, may continuously be formed.

The image sensing device 10 c having the above-described arrangement hasthe same function and effect as those of the image sensing device 10 bof the third embodiment. The image sensing device 10 c includes asmaller number of components and has a simpler structure than the imagesensing device 10 b of the third embodiment.

In this embodiment, the case member 514 is arranged as a componentseparated from the prism unit 30. The prism unit 30 is fixed in the casemember 514 and rotates on the pivot support portion 515 together withthe case member 514. Hence, the prism unit may include the case member514.

In this embodiment, the distance between an exit surface 64 of the prismunit 30 and the light-receiving surface of the image sensing element 12is adjusted by jacking up the prism unit 30 by using an adjustment screw516 b. This adjustment may be done by another method. For example, athrough hole is formed in an adjustment piece 516 a. The adjustmentscrew 516 b is inserted to the through hole of the adjustment piece 516a and threadably engaged with the threaded hole of the fixing member 513to move the prism unit in the direction in which the prism unitapproaches the image sensing element. In this case, the urging directionof the helical torsion spring 517 in the third embodiment is set in areverse direction. The step 518 in the fourth embodiment is set to beslightly larger.

An image sensing device 10 d according to the fifth embodiment of thepresent invention will be described with reference to FIGS. 33 to 41.The image sensing device 10 d has a mechanism which moves a prism unit30 in a direction crossing the light-receiving surface of an imagesensing element 12 and, more preferably, in a direction perpendicular tothe light-receiving surface of the image sensing element 12. For thedescriptive convenience, the direction perpendicular to thelight-receiving surface of the image sensing element 12 will be definedas an X direction, the direction in which a first prism 41 and a secondprism 42 are arranged will be defined as a Y direction, and thedirection perpendicular to the Y and X directions will be defined as a Zdirection in the drawings. As shown in FIG. 33, the image sensing device10 d comprises a fixing member 613, case member 614, link mechanism 615,switching member 616, and fine adjustment mechanism 670 in addition tothe above-described prism unit 30 and image sensing element 12.

The fixing member 613 is arranged between the prism unit 30 and theimage sensing element 12. The fixing member 613 has a window 613 a atthe central portion. The fixing member 613 locates and fixes thelight-receiving surface of the image sensing element 12 on an exitoptical axis λo such that a light beam which exits from the second prism42 of the prism unit 30 passes through the window 613 a and forms animage on the light-receiving surface of the image sensing element 12.The fixing member 613 on the side of the first prism 41 has guideportions 613 b along the Y direction in which the first prism 41 andsecond prism 42 are arranged. Mounting holes 613 d and 613 e are formed,at a total of four portions near the first prism 41 and second prism 42,in two side portions 613 c of the fixing member 613 in the widthwisedirection (Z direction) of the prism unit 30, which is perpendicular toan X-Y plane along which an incident optical axis λi and the exitoptical axis λo pass. First support shafts 613 f and 613 g serving asfirst link support portions that support the link mechanism 615 areinserted to the mounting holes 613 d and 613 e.

The case member 614 has a box shape which covers the prism unit 30except its surface on the side of the fixing member 613. The prism unit30 is mounted in the case member 614. The case member 614 has anincident window 614 a at a portion through which the light beam thatshould enter the first prism 41 of the prism unit 30 passes. Aprotective glass 614 b is fitted in the incident window 614 a. As theprotective glass 614 b, IR-blocking glass is preferably used. Mountingholes 614 d and 614 e are formed, at a total of four portions near thefirst prism 41 and second prism 42, in two side portions 614 c of thecase member 614 in the Z direction. Second support shafts 614 f and 614g serving as second link support portions of the link mechanism 615 areinserted to the mounting holes 614 d and 614 e.

As shown in FIGS. 36 and 37, the prism unit 30 comprises holding plates631. The holding plates 631 are arranged in parallel to planes A1 and A2(X-Y plane) along which the incident optical axis λi and exit opticalaxis λo pass so that the first prism 41 and second prism 42 aresandwiched from both sides in the widthwise direction (Z direction). Theholding plates 631 may be either integrated with an aperture member 43or attached as separate components. Engaging pins 632 which extend inthe Z direction are arranged on both sides of the holding plate 631. Theengaging pins 632 are inserted to engaging holes 614 h formed in thecase member 614 to connect the case member 614 and the prism unit 30.First fine adjustment abutment portions 631 a formed into a convex shapeprojecting toward the fixing member 613 are formed at four corners ofthe holding plates 631 facing the fixing member 613.

In stead of fitting the engaging pins 632 in the engaging holes 614 h tomount the prism unit 30 in the case member 614, the holding plates 631may be bonded and fixed directly on the inner surfaces of the casemember 614. Any other method can be used to fix the prism unit 30directly inside the case member 614.

The link mechanism 615 operatively connects the fixing member 613 andprism unit 30 to shift the prism unit 30 along the directionperpendicular to the light-receiving surface of the image sensingelement 12 while maintaining the posture of the prism unit 30. Toimplement this arrangement, in this embodiment, the link mechanism 615comprises first arm portions 615 a, second arm portions 615 b, supportpins 615 c, and urging members 615 d.

Each first arm portion 615 a has a pivot hole 615 f at one end 615 e. Along hole 615 h having a major axis in a direction along the first armportion 615 a is formed at the other end 615 g. Each second arm portion615 b has a pivot hole 615 q at one end 615 p. A long hole 615 s havinga major axis in a direction along the second arm portion 615 b is formedat the other end 615 r. The first arm portion 615 a and second armportion 615 b are rotationally supported by the support pin 615 cbetween the ends 615 e and 615 p and the other ends 615 g and 615 r.

One end 615 e of each first arm portion 615 a is rotationally supportedby the first support shaft 613 f on the side of the first prism 41. Theother end 615 g is slidably supported by the second support shaft 614 gon the side of the second prism 42. One end 615 p of each second armportion 615 b is rotationally supported by the second support shaft 614f on the side of the first prism 41. The other end 615 r is slidablysupported by the first support shaft 613 g on the side of the secondprism 42. The urging member 615 d urges the first arm portion 615 a andsecond arm portion 615 b in a direction in which they rotate on thesupport pin 615 c and overlap each other.

In this embodiment, the first arm portion 615 a and second arm portion615 b are rotationally supported by the first support shaft 613 f andsecond support shaft 614 f, respectively, on the side of the first prism41. However, the first arm portion 615 a and second arm portion 615 bmay be rotationally supported by the first support shaft 613 g andsecond support shaft 614 g, respectively, on the side of the secondprism 42. The link mechanism 615 need only operatively connect thefixing member 613 and prism unit 30 to shift the prism unit 30 in thedirection perpendicular to the light-receiving surface of the imagesensing element 12 while maintaining its posture. Hence, in place of thecase member 614, a support member designed to connect the prism unit 30to the link mechanism 615 may be applied.

The switching member 616 has a function of selectively positioning andholding the prism unit 30 at a first position P1 or second position P2along the direction perpendicular to the light-receiving surface of theimage sensing element 12. The first position P1 is, e.g., the standardimage sensing position shown in FIG. 2. The second position P2 isfarther from the light-receiving surface than the first position P1 andis, e.g., the macro image sensing position shown in FIG. 2. To make theswitching operation possible, in this embodiment, the switching member616 is arranged between the link mechanism 615 and the fixing member613, as shown in FIGS. 34 to 37. The switching member 616 can move inthe Y direction in which the first prism 41 and second prism 42 arearranged. The switching member 616 has abutment portions 616 a and slideholes 616 b.

The abutment portions 616 a abut against the support pins 615 c whichrotationally insert the first arm portions 615 a and second arm portions615 b and project to the side of the prism unit 30. Each abutmentportion 616 a has a first abutment portion 616 c, second abutmentportion 616 d, and slant 616 e. The first abutment portions 616 c locatethe prism unit 30 at the first position P1. The second abutment portions616 d locate the prism unit 30 at the second position P2. The slants 616e make the prism unit movable between the first position P1 and thesecond position P2 while keeping the support pins 615 c in a slidablecontact with the slants 616 e. Since the link mechanism 615 has theurging members 615 d, the support pins 615 c are always pressed againstthe abutment portions 616 a.

Each slide hole 616 b is a long hole whose major axis is arranged in thedirection in which the switching member 616 moves. The switching member616 has the slide holes 616 b at positions corresponding to the firstsupport shafts 613 f and 613 g. As shown in FIG. 36, the first supportshafts 613 f and 613 g are inserted to the slide holes 616 b of theswitching member 616. The first arm portions 615 a, second arm portions615 b, and switching member 616 are arranged such that they overlap inthe Z direction. Hence, to prevent the first arm portions 615 a, secondarm portions 615 b, and switching member 616 from twisting, anappropriate number of spacer washers 618 are attached to necessaryportions of the first support shafts 613 f and 613 g and second supportshafts 614 f and 614 g in accordance with their thicknesses.

The switching member 616 is arranged along the direction parallel to thelight-receiving surface of the image sensing element 12 to be movablebetween a first setting position S1 and a second setting position S2 inthe Y direction in which the first prism 41 and second prism 42 arearranged. The switching member 616 interlocks-with, e.g., a manualoperation switching member 95 which is arranged on a housing 2 of adigital camera 1 shown in FIG. 1.

As shown in FIG. 33, the fine adjustment mechanism 670 is arrangedbetween the fixing member 613 and the prism unit 30. The fine adjustmentmechanism 670 finely adjusts the first position P1 of the prism unit 30along the direction perpendicular to the light-receiving surface of theimage sensing element 12. The fine adjustment mechanism 670 has secondfine adjustment abutment portions 671 in correspondence with the firstfine adjustment abutment portions 631 a formed at the corners of theholding plate 631.

The second fine adjustment abutment portions 671 abut against the firstfine adjustment abutment portions 631 a while the prism unit 30 islocated and held at the first position P1. The second fine adjustmentabutment portions 671 slightly tilt to the side of the first prism 41with respect to the X direction perpendicular to the light-receivingsurface of the image sensing element 12. Hence, when the fine adjustmentmechanism 670 is moved in the Y direction, the prism unit 30 isdisplaced in the X direction while being supported by the link mechanism615 together with the case member 614. An end portion 670 a of the fineadjustment mechanism 670 is fitted on the guide portion 613 b of thefixing member 613 on the side of the first prism 41. After the firstposition P1 of the prism unit 30 is adjusted to an appropriate position,the fine adjustment mechanism 670 is fixed to the fixing member 613 byan adhesive or the like.

The operation of the image sensing device 10 d in switching the prismunit 30 between the first position P1 and the second position P2 will bedescribed next. FIGS. 38 and 39 show a state in which the first positionP1 of the prism unit 30 is finely adjusted by the fine adjustmentmechanism 670. When the first position P1 is finely adjusted by the fineadjustment mechanism 670, the first fine adjustment abutment portions631 a abut against the second fine adjustment abutment portions 671, asshown in FIG. 39. Accordingly, the support pins 615 c are separated fromthe first abutment portions 616 c, as shown in FIG. 38.

When the switching member 616 is moved in the Y direction to switch theprism unit 30 to the second position P2, the support pins 615 c of thelink mechanism 615 come into contact with the slants 616 e of theabutment portions 616 a during movement of the switching member 616 andare displaced up to the second abutment portions 616 d in a direction inwhich the prism unit separates from the light-receiving surface of theimage sensing element 12 along the X direction perpendicular to thelight-receiving surface. When the support pins 615 c move in the Xdirection, the angle between the first arm portion 615 a and the secondarm portion 615 b changes. As a result, the prism unit 30 moves in thedirection in which it separates from the light-receiving surface of theimage sensing element 12 together with the case member 614 and islocated at the second position P2, as shown in FIGS. 40 and 41.

As described above, when, e.g., the manual operation switching member 95is operated, the first setting position S1 shown in FIGS. 38 and 39 andthe second setting position S2 shown in FIGS. 40 and 41 are switched. Atthe first setting position S1, the switching member 616 locates andholds the prism unit 30 at the finely adjusted first position P1, asshown in FIG. 39. At the second setting position S2, the switchingmember 616 locates and holds the prism unit at the second position P2,as shown in FIG. 41.

In this embodiment, the switching member 616 is arranged between thefixing member 613 and the link mechanism 615. Instead, the switchingmember 616 may be arranged outside the link mechanism 615. The supportpins 615 c which extend through the first arm portions 615 a and secondarm portions 615 b and project to separate from the prism unit 30 may besupported by the abutment portions 616 a.

An image sensing device 10 e according to the sixth embodiment of thepresent invention will be described with reference to FIGS. 42 to 47.The same reference numerals as in the image sensing device 10 d of thefifth embodiment denote components having the same functions in thesixth embodiment, and a description thereof will be omitted.

The image sensing device 10 e shown in FIG. 42 is different from theimage sensing device 10 d of the fifth embodiment in that the devicecomprises a support frame 614 k of a case member 614 between a fixingmember 613 and a fine adjustment mechanism 670, and the fine adjustmentmechanism 670 is fixed to the support frame 614 k. Hence, the fineadjustment mechanism 670 is moved integrally with a prism unit 30 by alink mechanism 615 along the direction perpendicular to thelight-receiving surface of an image sensing element 12 while keepingsecond fine adjustment abutment portions 671 abutting against first fineadjustment abutment portions 631 a arranged on a holding plate 631 ofthe prism unit 30.

The prism unit 30 is moved in the case member 614 by the fine adjustmentmechanism 670 in the X direction perpendicular to the light-receivingsurface of the image sensing element 12. The case member 614 thereforehas long engaging holes 614 m having a major axis in the X direction atpositions corresponding to engaging pins 632 arranged on the holdingplate 631 of the prism unit 30.

In the image sensing device 10 e having the above-described structure,the case member 614 and fine adjustment mechanism 670 integrally movetogether with the prism unit 30. At a first position P1, support pins615 c are in contact with first abutment portions 616 c of a switchingmember 616 at a first setting position S1, as shown in FIG. 44. Inaddition, the first fine adjustment abutment portions 631 a of theholding plate 631 are in contact with the second fine adjustmentabutment portions 671 of the fine adjustment mechanism 670, as shown inFIG. 45. At a second position P2, the support pins 615 c are in contactwith second abutment portions 616 d of the switching member 616 at asecond setting position S2, as shown in FIG. 46. In addition, the firstfine adjustment abutment portions 631 a of the holding plate 631 are incontact with the second fine adjustment abutment portions 671 of thefine adjustment mechanism 670, as shown in FIG. 47.

That is, the image sensing device 10 e can finely adjust at least one ofthe first position P1 and second position P2 by using the fineadjustment mechanism 670. In this case, the conditions of the firstposition P1 and second position P2 may be compared. One of the positionsmay be adjusted with a particular emphasis on it, or setting may be donewhile balancing the conditions well.

An adjustment mechanism 686 serving as an adjustment means applied to animage sensing device according to the seventh embodiment of the presentinvention will be described with reference to FIGS. 48 and 49. Theadjustment mechanism 686 shown in FIG. 48 has both functions of theswitching member 616 and fine adjustment mechanism 670 of theabove-described embodiments. The adjustment mechanism 686 comprises anadjustment member 686 a, first fine adjustment cam 686 b, and secondfine adjustment cams 686 c.

The adjustment member 686 a has adjustment slants 686 d which tilt tothe side of a first prism 41. The adjustment slants 686 d may tilt tothe side of a second prism 42. Each adjustment slant 686 d has at itspart a first abutment portion 616 c and second abutment portion 616 d.The first abutment portions 616 c locate a prism unit 30 at a firstposition P1 shown in FIG. 2. The second abutment portions 616 d locatethe prism unit 30 at a second position P2 shown in FIG. 2. Theadjustment member 686 a can move along the Y direction in FIG. 48 inwhich the first prism 41 and second prism 42 are arranged.

When the adjustment member 686 a is at a first setting position S1, thefirst fine adjustment cam 686 b abuts against an end portion 686 e ofthe adjustment member 686 a on the side of the second abutment portions616 d and is eccentric in the Y direction about a first cam shaft M1arranged along the X direction. The first setting position S1 of theadjustment member 686 a which positions the prism unit 30 at the firstposition P1 is finely adjusted in the Y direction. Accordingly, thefirst position P1 of the prism unit 30 is set to an appropriateposition.

When the adjustment member 686 a is at a second setting position S2, thesecond fine adjustment cams 686 c abut against end portions 686 f of theadjustment member 686 a on the side of the first abutment portions 616 cand are decentered in the Y direction about a second cam shaft M2arranged along the X direction. The second setting position S2 of theadjustment member 686 a which positions the prism unit 30 at the secondposition P2 is finely adjusted in the Y direction. Accordingly, thesecond position P2 of the prism unit 30 is set to an appropriateposition.

As described above, the adjustment member 686 a can locate the prismunit 30 at the first position P1 and second position P2 by using theadjustment slants 686 d and also finely adjust the first position P1 andsecond position P2.

An image sensing device 10 f according to the eighth embodiment of thepresent invention will be described with reference to FIGS. 50 to 52. Asshown in FIG. 50, a prism unit 30 of the image sensing device 10 f isaccommodated in a case 770. The case 770 has an incident window 771 at aposition opposing an incident surface 51 of a first prism 41. As shownin FIG. 51, a pair of guide members 775 and 776 are formed on a fixingframe 731. The guide members 775 and 776 are fitted in engaging portions777 (only one of them is illustrated) formed on the case 770.

The image sensing device 10 f comprises a guide mechanism 780 to guidethe prism unit 30 movably in a direction perpendicular to thelight-receiving surface of an image sensing element 12. The guidemechanism 780 guides the prism unit 30 movably in the X direction alongthe direction (the direction indicated by an arrow X in FIG. 50)perpendicular to the light-receiving surface of the image sensingelement 12 while maintaining the posture of the prism unit 30.

The guide mechanism 780 includes guide grooves 781 as an example ofguide portions formed in the case 770, convex guided portions 782 whichfit in the guide grooves 781 and freely move in the X direction, andabutment portions 783 which abut against a switching member 791 to bedescribed later. The guided portions 782 and abutment portions 783 areformed on both side surfaces of an aperture member 43. The guidedportions 782 and abutment portions 783 may be formed on the first prism41 or a second prism 42.

Each guided portion 782 is formed from a convex portion having twoparallel surfaces 785 and 786. When the two parallel surfaces 785 and786 come into contact with the inner surfaces of the guide groove 781,the prism unit 30 can move straight in the X direction. The abutmentportions 783 can have any shape and, for example, a cylindrical pin-likeshape and come into contact with positioning surfaces 792 of theswitching member 791 which forms a switching mechanism 790.

The switching member 791 has a function of selectively positioning andholding the prism unit 30 at a first position (e.g., the standard imagesensing position shown in FIG. 2) P1 or a second position P2 (e.g., themacro image sensing position) farther from the light-receiving surfaceof the image sensing element 12 than the first position P1 along theguide mechanism 780. The switching member 791 can move reciprocally in adirection (a direction parallel to the light-receiving surface of theimage sensing element 12) indicated by an arrow Y in FIG. 50 withrespect to the fixing frame 731 and case 770.

The switching member 791 can be switched between a first settingposition S1 and a second setting position S2 by, e.g., a manualoperation switching member 95 arranged on a housing 2 of a digitalcamera 1 shown in FIG. 1. The manual operation switching member 95interlocks with the switching member 791 of the switching mechanism 790and is used to selectively locate the switching mechanism 790 at thefirst setting position S1 or second setting position S2.

The switching member 791 can move between the first setting position S1and the second setting position S2 along the direction (the directionindicated by the arrow Y in FIG. 50) parallel to the light-receivingsurface of the image sensing element 12. Each positioning surface 792formed on the switching member 791 has a first plane portion 792 a,second plane portion 792 b, and slant portion 792 c along the direction(Y direction) parallel to the light-receiving surface of the imagesensing element 12. The first plane portion 792 a is parallel to thelight-receiving surface of the image sensing element 12. The secondplane portion 792 b is parallel to the light-receiving surface and islocated at a position different from the first plane portion 792 a inthe direction perpendicular to the light-receiving surface. The slantportion 792 c is located between the first plane portion 792 a and thesecond plane portion 792 b.

A predetermined portion midway in the longitudinal direction of thefirst plane portion 792 a functions as a first face portion to locatethe prism unit 30 at the first position P1. A predetermined portionmidway in the longitudinal direction of the second plane portion 792 bfunctions as a second face portion to locate the prism unit 30 at thesecond position P2.

The case 770 has guide portions 7100 serving as a switching member guidemechanism. The guide portions 7100 function to move the switching member791 of the switching mechanism 790 straight along the direction (Ydirection) parallel to the light-receiving surface of the image sensingelement 12.

The positioning surfaces 792 formed on the switching member 791 abutagainst the abutment portions 783 of the prism unit 30. Since the slantportion 792 c is formed between the first plane portion 792 a and thesecond plane portion 792 b of the positioning surface 792, the abutmentportion 783 can smoothly move between the first plane portion 792 a andthe second plane portion 792 b.

A spring 7101 is arranged as an example of a press mechanism to make theabutment portion 783 abut against the positioning surface 792. Theabutment portion 783 is urged toward the positioning surface 792 by theelastic force of the spring 7101. The spring 7101 is attached to, e.g.,the case 770.

The image sensing device 10 f has a fine adjustment mechanism 7110 tofinely adjust at least one (e.g., the first position P1) of the firstposition P1 and second position P2 in the direction perpendicular to thelight-receiving surface of the image sensing element 12. An example ofthe fine adjustment mechanism 7110 includes the guide members 775 and776 formed on the fixing frame 731 and the engaging portions 777 (onlyone of them is illustrated in FIG. 50) formed on the case 770.

The guide members 775 and 776 and engaging portions 777 can relativelymove in the direction (X direction) perpendicular to the light-receivingsurface of the image sensing element 12. That is, the prism unit 30 canmove in the X direction integrally with the case 770 and switchingmechanism 790. Accordingly, the prism unit 30 can finely adjust at leastone of the first position P1 and the second position P2. That is, theposition of the prism unit 30 can finely be adjusted in the directionperpendicular to the light-receiving surface of the image sensingelement 12.

In fc adjustment of the image sensing device 10 f, for example, as shownin FIG. 52, the case 770 is held by a jig 7121 having a grip mechanism7120, and the relative position between the grip mechanism 7120 and abase member 7123 is finely adjusted by an adjustment member 7122 such asa screw, thereby adjusting a distance G between the fixing frame 731 andthe case 770.

When the distance G between the fixing frame 731 and the case 770 isadjusted, fc adjustment can be done at, e.g., the standard image sensingposition. In this case, to prevent the fixing frame 731 from movingduring the fc adjustment, the fixing frame 731 is held at apredetermined position by a fixing jig 7125. In the fc adjustment, anadjustment test chart is placed at an object position suitable forstandard image sensing. The contrast value of image data is evaluated onthe basis of an electrical signal from the image sensing element. Fineadjustment is executed such that the contrast value is maximized. Adetailed description of this operation will be omitted.

After the fc adjustment, the guide members 775 and 776 and engagingportion 777 are bonded by, e.g., an adhesive. Accordingly, the distancefrom the prism unit 30 to the image sensing element 12 is fixed at aposition where the focal plane to the image sensing element 12 isadjusted.

In this embodiment, adjustment is done such that the best imaging stateis obtained at the standard image sensing position. Instead, fcadjustment may be done such that the best imaging state is obtained atthe macro image sensing position without any particular adjustment forthe imaging state at the standard image sensing position.

The operation of the image sensing device 10 f having the switchingmechanism 790 and fine adjustment mechanism 7110 will be described next.The switching member 791 is moved to the first setting position S1 bythe manual operation switching member 95 shown in FIG. 1 or the like. Inthis case, the abutment portions 783 abut against the first faceportions in the first plane portions 792 a so that the prism unit 30 isset at the standard image sensing position.

When the switching member 791 is moved to the second setting positionS2, the abutment portions 783 abut against the second face portions inthe second plane portions 792 b so that the prism unit 30 is set at themacro image sensing position. The manual operation switching member 95is operatively connected to the switching member 791, although nodetailed mechanism is illustrated.

In the image sensing device 10 f, the position of the focal plane canfinely be adjusted by fc adjustment. For this reason, the positionalshift between an imaging plane 45 of the prism unit 30 and thelight-receiving surface of the image sensing element 12, which is causedby an inevitable variation between components or accuracy of form ofeach component at the time of assembling the image sensing device 10 f,can be minimized. Hence, the image sensing device 10 f can form asatisfactory image.

FIGS. 53 to 56 show an image sensing device 10 g according to the ninthembodiment which further embodies the present invention. The basicarrangement and function of the image sensing device 10 g are the sameas those of the image sensing device 10 f of the eighth embodiment. Thesame reference numerals as in the image sensing device 10 f of theeighth embodiment denote the same parts in the ninth embodiment.

The image sensing device 10 g of the eighth embodiment comprises afixing frame 731 having an image sensing element 12, a case 770, a prismunit 30 accommodated in the case 770, a guide mechanism 780, guideportions 7100 which function as a switching member guide mechanism, andguide members 775 and 776 and engaging portions 777 and 777′ which forma fine adjustment mechanism 7110, as in the eighth embodiment.

As shown in FIG. 53, a switching mechanism 790 has a switching member791 which can move to a first setting position S1 shown in FIG. 54 or asecond setting position S2 shown in FIG. 56. When the switching member791 is moved to the first setting position S1, the prism unit 30 movesto a first position P1 (e.g., the standard image sensing position), asshown in FIG. 55. When the switching member 791 is moved to the secondsetting position S2, the prism unit 30 moves to a second position P2(e.g., the macro image sensing position). The image sensing device 10 gcomprises a regulating member 7129 (FIGS. 53 and 54) to stop theswitching member 791 at the first setting position S1 or second settingposition S2.

FIG. 57 shows an image sensing device 10 h according to the 10thembodiment of the present invention. The basic arrangement and functionof the image sensing device 10 h are the same as those of the imagesensing device 10 f of the eighth embodiment. The image sensing device10 h comprises a screw member 7130 as a fine adjustment mechanism 7110for fc adjustment. When the screwing amount of the screw member 7130 toa fixing frame 731 is adjusted, a distance G between the fixing frame731 and a case 770 is finely adjusted. Accordingly, adjustment (fcadjustment) of the focal plane of a prism unit 30 can be done.

FIG. 58 shows an image sensing device 10 i according to the 11thembodiment of the present invention. Each positioning surface 792 of aswitching mechanism 790 of the image sensing device 10 i includes a camslant 7140 formed from slants whose coordinates in the directionperpendicular to the light-receiving surface of the image sensingelement are different. Abutment portions 783 abut against the cam slants7140.

Each cam slant 7140 has a first face portion 7141 which functions as afirst face portion to locate a prism unit 30 at a first position P1 anda second face portion 7142 to locate the prism unit 30 at a secondposition P2. The first face portion 7141 and second face portion 7142are formed in line along the direction parallel to the image sensingelement. The first face portion 7141 is a first part in the cam slant7140. The second face portion 7142 is a second part in the cam slant7140 different from the first part.

As in the image sensing device 10 i of this embodiment, when theabutment portions 783 are made to abut against the first face portions7141 or second face portions 7142 midway in the cam slants 7140, thefirst position (e.g., the standard image sensing position) and thesecond position (e.g., the macro image sensing position) can beswitched. The image sensing device 10 i comprises regulating members7150 and 7151. The regulating members 7150 and 7151 function as stoppersto regulate the moving range of the switching member 791 in thedirection parallel to the light-receiving surface of the image sensingelement.

Examples of the regulating members 7150 and 7151 are eccentric pinswhich rotate about shafts 7152 and 7153. The regulating members 7150 and7151 are rotated, thereby regulating the position (a first settingposition S1 or second setting position S2) of the switching member 791.Accordingly, the position of the first face portion 7141 or second faceportion 7142 which is in contact with the abutment portion 783 canfinely be adjusted. With the above-described arrangement, the prism unit30 can be switched between the first position (e.g., the standard imagesensing position) and the second position (e.g., the macro image sensingposition). In addition, fine adjustment (fc adjustment) of the focalplane of the prism unit 30 can be done.

FIGS. 59 and 60 show an image sensing device 10 j according to the 12thembodiment of the present invention. The basic arrangement and functionof the image sensing device 10 j are the same as those of the imagesensing device 10 i of the 11th embodiment. The same reference numeralsas in the image sensing device 10 i of the 11th embodiment denote thesame parts in the 12th embodiment. The shape of a switching member 791and the modes of a case 770, fixing frame 731, and spring 7101 arefurther embodied as compared in the 11th embodiment.

Each positioning surface 792 of a switching mechanism 790 of the imagesensing device 10 j also includes a cam slant 7140 formed from slantswhose coordinates in the direction perpendicular to the light-receivingsurface of an image sensing element 12 are different, as in the imagesensing device 10 i of the 11th embodiment. Abutment portions 783 abutagainst the cam slants 7140.

A first face portion 7141 and a second face portion 7142 are formed onthe cam slant 7140 in line along the direction parallel to the imagesensing element 12. The first face portion 7141 locates a prism unit 30at a first position P1. The second face portion 7142 locates the prismunit 30 at a second position P2.

Even in the image sensing device 10 j having the above-describedarrangement, when the abutment portions 783 selectively abut against thefirst face portions 7141 or second face portions 7142 on the cam slants7140, the standard image sensing position and the macro image sensingposition can be switched. In addition, the position of a switchingmember 791 is finely adjusted by regulating members 7150 and 7151, theposition of the first face portion 7141 or second face portion 7142which is in contact with the abutment portion 783 can finely beadjusted. Hence, fine adjustment (fc adjustment) of the focal plane ofthe prism unit 30 can be done.

An image sensing device 10 k according to the 13th embodiment of thepresent invention will be described with reference to FIGS. 61 to 64. Aprism unit 30 of the image sensing device 10 k comprises a case 870which accommodates a first prism 41, second prism 42, and aperturemember 43, as shown in FIGS. 61 to 64. The case 870 has an incidentwindow 871 at a position opposing an incident surface 51 of the firstprism 41.

The image sensing device 10 k of this embodiment comprises an adjustmentmechanism 880. The adjustment mechanism 880 has an adjustment member 881which can move in a direction (a first direction indicted by an arrow Zin FIGS. 61 to 63) parallel to the light-receiving surface of an imagesensing element 12 in fc adjustment. The prism unit 30 is finelyadjusted by the adjustment member 881 in a direction (a second directionindicated by an arrow X in FIGS. 61, 63, and 64) perpendicular to thelight-receiving surface of the image sensing element 12. The adjustmentmechanism 880 will be described below.

The adjustment mechanism 880 has the adjustment member 881 which canmove in the Z direction as the first direction parallel to thelight-receiving surface of the image sensing element 12, and a receivingportion 882 arranged on the prism unit 30. The receiving portion 882 isformed on, e.g., a frame member 870 a which forms part of the case 870to finely adjust the position of the prism unit 30 in the X direction asthe second direction. The receiving portion 882 abuts against theadjustment member 881.

The portion of the adjustment member 881 which abuts against thereceiving portion 882 is a slant 883 whose X-direction position changesalong the Z direction. The receiving portion 882 has an incline 884conforming to the slant 883 at the portion which abuts against the slant883 of the adjustment member 881. As shown in FIG. 63, tilt angles θ ofthe slants 883 and 884 coincide with each other.

The slant 883 formed on the adjustment member 881 abuts against theincline 884 of the receiving portion 882. For this reason, when theadjustment member 881 is moved in the Z direction in fc adjustment, theprism unit 30 moves by a small amount in the X direction in accordancewith the tilt angle θ of the-slants 883 and 884 while maintaining itsposture.

As shown in FIG. 62, an example of the adjustment member 881 has a pairof first portions 890 and 891 which are arranged at both ends of theprism unit 30 and abut against the receiving portion 882, and secondportions 892 and 893 which connect the first portions 890 and 891. An fcadjustment jig 8100 (FIG. 61) to move the adjustment member 881 in the Zdirection comes into contact with at least one of the first portions 890and 891. An example of the fc adjustment jig 8100 is an eccentric pin8102 which rotates about a shaft 8101.

After the fc adjustment, in a state in which the first portions 890 and891 are fixed at predetermined positions with respect to the prism unit30, the second portions 892 and 893 of the adjustment member 881 areseparated from the first portions 890 and 891. For example, the secondportions 892 and 893 are separated from the first portions 890 and 891at cutting presumptive portions 8110 indicated by alternate long andtwo-dashed lines in FIGS. 61 and 62.

At the two ends of a fixing frame 831 having the image sensing element12, first guide portions 8111 to guide the adjustment member 881 in theZ direction are formed at positions corresponding to the first portions890 and 891 of the adjustment member 881. Hence, the adjustment member881 can smoothly move straight in the Z direction.

As shown in FIG. 64, second guide portions 8112 to guide, e.g., theframe member 870 a of the case 870 in the X direction at the time of fcadjustment such that the prism unit 30 can move in the second directionY are formed on the fixing frame 831.

With the above-described arrangement, the prism unit 30 including thecase 870 can move in the X direction perpendicular to thelight-receiving surface of the image sensing element 12 relative to thefixing frame 831 in fc adjustment. That is, the position of the prismunit 30 in the X direction perpendicular to the light-receiving surfaceof the image sensing element 12 can finely be adjusted.

The image sensing device 10 k has fixing portions 8115 (FIG. 63) to fixthe adjustment member 881 to the prism unit 30 by bonding or the likeafter the fc adjustment. Examples of the fixing portions 8115 are thefirst portions 890 and 891 of the adjustment member 881. The fixingportions 8115 only need to fix the prism unit 30 to the fixing frame 831in the X direction after the fc adjustment. Hence, the positions of thefixing portions 8115 are not limited to that shown in FIG. 63. The prismunit 30 may be fixed to the fixing frame 831 by any other fixing meansthan an adhesive.

The function of the image sensing device 10 k of this embodiment will bedescribed below. As shown in FIG. 61, the fixing frame 831 is held by afixing jig 8120. In a state in which the adjustment member 881 isarranged at an initial position Q1, the eccentric pin 8102 is rotated tomove the adjustment member 881 in a direction indicated by an arrow F.At this time, when the position of the prism unit 30 in the X directionis finely adjusted in accordance with the position of the adjustmentmember 881 in the Z direction, a distance G between the prism unit 30and the fixing frame 831 is adjusted. Hence, fine adjustment (fcadjustment) of the focal plane of the prism unit 30 can be done.

In the fc adjustment, an adjustment test chart is placed at an objectposition suitable for standard image sensing. The contrast value ofimage data is evaluated on the basis of an electrical signal from theimage sensing element. Fine adjustment is executed such that thecontrast value is maximized. A detailed description of this operationwill be omitted.

After the fc adjustment, for example, the case 870 and fixing frame 831are fixed at the fixing portions 8115 of the first portions 890 and 891which abut against the receiving portion 882 of the adjustment member881 by using, e.g., an adhesive 8121 (schematically shown in FIG. 63).Accordingly, the distance from the prism unit 30 to the image sensingelement 12 is fixed at a position where the focal plane to the imagesensing element 12 is adjusted. After the fixing portions 8115 arefixed, the second portions 892 and 893 of the adjustment member 881 areseparated from the first portions 890 and 891 at the cutting presumptiveportions 8110.

As described above, in the manufacturing method according to thisembodiment, the step of assembling the prism unit 30, image sensingelement 12, and adjustment mechanism 880, the step of fixing the prismunit 30 to the fixing frame 831 at the first portions 890 and 891 of theadjustment member 881, and the step of separating the second portions892 and 893 of the adjustment member 881 are executed in this order.

In this embodiment, the second portions 892 and 893 of the adjustmentmember 881 are separated after the fc adjustment. In some products, theimage sensing element 12 may be used without separating the secondportions 892 and 893.

In the image sensing device 10 k having the above-described arrangement,the position of the focal plane can finely be adjusted by fc adjustment.For this reason, the positional shift between an imaging plane 45 of theprism unit 30 and the light-receiving surface of the image sensingelement 12, which is caused by an inevitable variation betweencomponents or accuracy of form of each component at the time ofassembling the image sensing device 10 k, can be minimized. Hence, theimage sensing device 10 k can form a satisfactory image.

FIG. 65 shows another example of the adjustment jig 8100. Thearrangement of the image sensing device 10 k is the same as in the 13thembodiment except a screw member 8130 is used as the fc adjustment jig8100. The screw member 8130 can finely adjust the position of theadjustment member 881 in the Z direction by adjusting the screwingamount to a fixing-side member 8131.

An image sensing device 10 m according to the 14th embodiment of thepresent invention will be described with reference to FIGS. 66 to 70Aand 70B. As shown in FIGS. 66 to 68, a prism unit 30 of the imagesensing device 10 m comprises a case 970 which accommodates a firstprism 41, second prism 42, and aperture member 43. The case 970 has anincident window 971 at a position opposing an incident surface 51 of thefirst prism 41.

The image sensing device 10 m comprises a guide mechanism 980 to guidethe prism unit 30 to be movable in a direction (a direction indicated byan arrow X in FIG. 67) perpendicular to the light-receiving surface ofan image sensing element 12. An example of the guide mechanism 980 has acylindrical pin-shaped shaft 981 formed at the left end of a fixingframe 931 in FIG. 67 and a guide member 982 which is formed at the rightend of the fixing frame 931.

As shown in FIG. 68, the shaft 981 fits in a fitting hole 983 formed ata part 970 a of the case 970 to be movable in the X direction. The guidemember 982 engages with an engaging portion 984 (FIG. 67) formed on thecase 970 to be movable in the X direction. The prism unit 30 is guidedby the guide mechanism 980 and moved in the X direction whilemaintaining its posture in the direction perpendicular to thelight-receiving surface of the image sensing element 12.

The image sensing device 10 m has a switching mechanism 990. Theswitching mechanism 990 includes the shaft 981 extending in thedirection perpendicular to the light-receiving surface of the imagesensing element 12, and a switching member 991 which can rotate on theshaft 981. The switching mechanism 990 has a function of selectivelymoving the prism unit 30 along the guide mechanism 980 to a firstposition P1 or second position P2 and holding its position. The firstposition P1 is, e.g., the standard image sensing position shown in FIG.2. The second position P2 is farther from the light-receiving surface ofthe image sensing element 12 than the first position P1 and is, e.g.,the macro image sensing position.

The switching member 991 can rotate on the shaft 981 in directionsindicated by an arrow U in FIG. 66, i.e., in a plane parallel to thelight-receiving surface of the image sensing element 12. Regulatingmembers 992 and 993 are arranged on the side of the fixing frame 931 toregulate the moving limit positions in the directions in which theswitching member 991 rotates in the plane parallel to thelight-receiving surface of the image sensing element 12.

The switching member 991 can be switched between a first settingposition Si shown in FIG. 70A and a second setting position S2 shown inFIG. 70B by, e.g., a manual operation switching member 95 arranged on ahousing 2 of a digital camera 1 shown in FIG. 1. The manual operationswitching member 95 interlocks with the switching member 991 of theswitching mechanism 990 and is used to selectively locate the switchingmechanism 990 at the first setting position S1 or second settingposition S2.

The switching member 991 can rotate between the first setting positionS1 and the second setting position S2 in the directions indicated by thearrow U. A positioning surface 9100 is formed on the switching member991. The positioning surface 9100 has a first plane portion 9101, secondplane portion 9102, and slant portion 9103. The first plane portion 9101is parallel to the light-receiving surface of the image sensing element12. The second plane portion 9102 is parallel to the light-receivingsurface and is located at a position (coordinates) different from thefirst plane portion 9101 in the direction perpendicular to thelight-receiving surface. The slant portion 9103 is located between thefirst plane portion 9101 and the second plane portion 9102. An operationportion 9104 is arranged as needed.

The operation portion 9104 is arranged in place of the above-describedmanual operation switching member 95. When the operation portion 9104 isexposed to the outer surface of the housing 2, the manual operationswitching member 95 is unnecessary. Although not illustrated in detail,if the operation portion 9104 projects from the upper surface of thecamera, the switching mechanism 990 can be operated by manuallyoperating the operation portion 9104. The operation portion 9104 may beswitched by using an actuator such as an electric motor. In this case aswell, the-manual operation switching member 95 is unnecessary.

A predetermined portion midway in the rotational direction of the firstplane portion 9101 functions as a first face portion to locate the prismunit 30 at the first position P1. A predetermined portion midway in therotational direction of the second plane portion 9102 functions as asecond face portion to locate the prism unit 30 at the second positionP2.

An abutment portion 9110 which abuts against the positioning surface9100 is formed on the side of the case 970. The abutment portion 9110 isformed at a position opposing the positioning surface 9100 and abutsagainst the plane portion 9101 or 9102 or the slant portion 9103 of thepositioning surface 9100 in accordance with the rotational position ofthe switching member 991.

Since the slant portion 9103 is formed between the first plane portion9101 and the second plane portion 9102, the abutment portion 9110 cansmoothly move between the first plane portion 9101 and the second planeportion 9102. The abutment portion 9110 is formed at part of the case970. However, it may be formed on the first prism 41 or second prism 42.The abutment portion 9110 may be formed on the aperture member 43. Inthis case, the number of components can be reduced.

A spring 9111 is arranged as an example of a press mechanism to make theabutment portion 9110 abut against the positioning surface 9100. Theabutment portion 9110 is urged toward the positioning surface 9100 bythe elastic force of the spring 9111. The spring 9111 is attached to,e.g., the fixing frame 931.

The function of the image sensing device 10 of the first embodiment willbe described below. FIG. 69 shows a state in which the switching member991 of the switching mechanism 990 is at the neutral position. Theswitching member 991 is located at one of the first plane portion 9101and second plane portion 9102 from this neutral position.

The switching member 991 is caused to rotate to the first settingposition S1 by, e.g., the manual operation switching member 95 shown inFIG. 1, as shown in FIG. 70A. Since the abutment portion 9110 abutsagainst the first face portion in the first plane portion 9101, theprism unit 30 is set at the standard image sensing position. At thistime, further pivot of the switching member 991 is inhibited by oneregulating member 992. The manual operation switching member 95 isoperatively connected to the switching member 991, although no detailedmechanism is illustrated.

The switching member 991 is caused to rotate to the second settingposition S2, as shown in FIG. 70B. The abutment portion 9110 abutsagainst the second face portion in the second plane portion 9102.Accordingly, the prism unit 30 is set at the macro image sensingposition. At this time, further rotation of the switching member 991 isinhibited by the other regulating member 993.

An image sensing device 10 n according to the 15th embodiment of thepresent invention will be described with reference to FIGS. 71 to 73Aand 73B. The basic arrangement of the image sensing device 10 n is thesame as that of the image sensing device 10 m of the 14th embodiment.The image sensing device 10 n of the 15th embodiment is different fromthe image sensing device 10 m of the 14th embodiment in that the devicehas a fine adjustment mechanism 9120. The same reference numerals as inthe image sensing device 10 m of the 14th embodiment denote the sameparts in the image sensing device 10 n.

The fine adjustment mechanism 9120 finely adjusts at least one (e.g.,the first position P1) of a first position P1 and second position P2 ofa prism unit 30 in a direction perpendicular to the light-receivingsurface of an image sensing element 12.

As shown in FIGS. 71 to 73A and 73B, an example of the fine adjustmentmechanism 9120 has a cam member 9121 which can rotate on a shaft 981.The cam member 9121 has a slant 9122 whose position in the directionperpendicular to the light-receiving surface of the image sensingelement 12 changes in the rotational direction. A receiving portion 9123formed on a switching member 991 of a switching mechanism 990 abutsagainst the slant 9122. The receiving portion 9123 is formed on asurface of the switching member 991 on the opposite side of apositioning surface 9100. The receiving portion 9123 may have an arcshape or an incline conforming to the slant 9122 of the cam member 9121of the fine adjustment mechanism 9120.

In fc adjustment of the image sensing device 10 n, the cam member 9121is caused to rotate on the shaft 981 relative to the switching member991. At this time, since the receiving portion 9123 slides on the slant9122, the prism unit 30 can finely adjust at least one of the firstposition P1 and the second position P2. That is, the position of theprism unit 30 can finely be adjusted in the direction (a directionindicated by an arrow X in FIG. 72) perpendicular to the light-receivingsurface of the image sensing element 12.

As described above, when the cam member 9121 is caused to rotate withrespect to the switching member 991 to adjust the distance from theprism unit 30 to the image sensing element 12 at the time of fcadjustment, fc adjustment can be done at, e.g., the standard imagesensing position.

In the fc adjustment, an adjustment test chart is placed at an objectposition suitable for standard image sensing. The contrast value ofimage data is evaluated on the basis of an electrical signal from theimage sensing element. The fine adjustment mechanism 9120 is finelyadjusted such that the contrast value is maximized. A detaileddescription of this operation will be omitted.

After the fc adjustment, the receiving portion 9123 is fixed to the cammember 9121. When the cam member 9121 is bonded to the switching member991 by, e.g., an adhesive, the distance from the prism unit 30 to theimage sensing element 12 is fixed at a position where the focal plane tothe image sensing element 12 is adjusted.

In this embodiment, adjustment is done such that the best imaging stateis obtained at the standard image sensing position. Instead, fcadjustment may be done such that the best imaging state is obtained atthe macro image sensing position without any particular adjustment forthe imaging state at the standard image sensing position.

The function of the image sensing device 10 n having the switchingmechanism 990 and fine adjustment mechanism 9120 will be described next.When the switching member 991 rotates to the first setting position S1,as shown in FIG. 73A, the abutment portion 9110 abuts against the firstface portion in the first plane portion 9101. The prism unit 30 islocated at the standard image sensing position. At this time, the cammember 9121 moves to a first setting position S1 integrally with theswitching member 991. The switching member 991 is stopped at the firstsetting position S1 by one regulating member 992.

When the switching member 991 rotates to a second setting position S2,as shown in FIG. 73B, the abutment portion 9110 abuts against the secondface portion in the second plane portion 9102. The prism unit 30 islocated at the macro image sensing position. At this time, the cammember 9121 moves to the second setting position S2 integrally with theswitching member 991. The switching member 991 is stopped at the secondsetting position S2 by the other regulating member 993.

In the image sensing device 10 n, the position of the focal plane isfinely adjusted by fc adjustment using the cam member 9121. For thisreason, the positional shift between the imaging plane of the prism unit30 and the light-receiving surface of the image sensing element 12,which is caused by an inevitable variation between components oraccuracy of form of each component at the time of assembling the imagesensing device 10 n, can be minimized. Hence, the image sensing device10 n can form a satisfactory image.

An image sensing device 10 p according to the 16th embodiment of thepresent invention will be described with reference to FIGS. 74, 75A, and75B. The basic arrangement of the image sensing device 10 p is the sameas that of the image sensing device 10 m of the 14th embodiment. Theimage sensing device 10 p of the 16th embodiment is different from theimage sensing device 10 m of the 14th embodiment in that the device hasa fine adjustment mechanism 9130 and a positioning surface 9100 of aswitching member 991 is mainly formed from a cam slant 9131. The samereference numerals as in the image sensing device 10 m of the 14thembodiment denote components having the same functions in the imagesensing device 10 p.

The positioning surface 9100 of the switching member 991 of the imagesensing device 10 p has the cam slant 9131 including the first faceportion and second face portion in a direction in which the switchingmember 991 rotates about a shaft 981. The first face portion and secondface portion are located at different positions in a directionperpendicular to the light-receiving surface of an image sensing element12. A predetermined portion midway in the rotational direction of thecam slant 9131 functions as the first face portion to locate a prismunit 30 at a first position P1. Another predetermined portion midway inthe rotational direction of the cam slant 9131 functions as the secondface portion to locate the prism unit 30 at a second position P2.

That is, the positioning surface 9100 of the image sensing device 10 pincludes the cam slant 9131 whose coordinates in the directionperpendicular to the light-receiving surface of the image sensingelement 12 change. An abutment portion 9110 abuts against the cam slant9131. The first face portion is a first part in the cam slant 9131. Thesecond face portion is a second part in the cam slant 9131 differentfrom the first part.

As in the image sensing device 10 p, when the abutment portion 9110 iscaused to abut against the first face portion or second face portionmidway in the cam slant 9131, the first position (e.g., the standardimage sensing position) and the second position (e.g., the macro imagesensing position) can be switched.

The fine adjustment mechanism 9130 of the image sensing device 10 pcomprises eccentric pins which rotate about shafts 9142 and 9143 asexamples of regulating members 9140 and 9141 to regulate the movingrange of the switching member 991 in the direction parallel to theperpendicular to the light-receiving surface of the image sensingelement 12.

As shown in FIG. 75A, one regulating member 9140 functions as a stopperto stop the switching member 991 at a first setting position S1. Asshown in FIG. 75B, the other regulating member 9141 functions as astopper to stop the switching member 991 at a second setting positionS2. The regulating members 9140 and 9141 are rotated about the shafts9142 and 9143 to finely adjust the first setting position S1 or secondsetting position S2. Accordingly, the position of the first face portionor second face portion in the cam slant 9131 in contact with theabutment portion 9110 can finely be adjusted.

According to the image sensing device 10 p having the above-describedarrangement, the prism unit 30 can be switched between the firstposition P1 (e.g., the standard image sensing position) and the secondposition P2 (e.g., the macro image sensing position). In addition, fineadjustment (fc adjustment) of at least one of the first position P1 andsecond position P2 of the prism unit 30, i.e., the focal plane can bedone. If no fc adjustment function is necessary, the regulating members992 and 993 serving as simple stoppers as shown in FIG. 66 can be usedin place of the regulating members 9140 and 9141.

An image sensing device 10 q according to the 17th embodiment of thepresent invention will be described with reference to FIG. 76. In theimage sensing device 10 q of this embodiment, the shape of an abutmentportion 9110′ which abuts against a positioning surface 9100 of aswitching member 991 conforms to a cam slant 9131 of the positioningsurface 9100. The 17th embodiment is the same as the 16th embodiment(FIGS. 74, 75A, and 75B) except that point.

FIG. 77 shows an example of an image sensing apparatus according to thepresent invention, in which a cellular phone 160 with a cameraincorporates an image sensing device. When the cellular phone 160 with acamera incorporates one (e.g., the image sensing device 10) of the imagesensing apparatuses described in the above embodiments, the cellularphone 160 with a camera can be compact and thin and increase the imagequality.

In the cellular phone 160 with a camera, the switching member of theswitching mechanism is switched between a first stable posture T1 (or afirst setting position S1) and a second stable posture T2 (or a secondsetting position S2) by a manual operation switching member 95. Insteadof using the manual operation switching member 95, the switching membermay be motor-driven by using an actuator such as an electric motor orsolenoid.

FIGS. 78 to 80 show different examples of prism units 30 a, 30 b, and 30c applied to the image sensing device of the present invention. All theprism units 30 a, 30 b, and 30 c can be switched between a firstposition P1 and a second position P2 by the same switching mechanism asin the image sensing apparatuses of the above-described embodiments.

In the prism unit 30 a shown in FIG. 78, all surfaces 201 to 206 of afirst prism 41 a and second prism 42 a are formed from free-formsurfaces. Light input from the first surface 201 is refracted by thefirst surface 201, totally reflected by the second surface 202,refracted by the third surface 203, and then refracted by the fourthsurface 204. The light is further totally reflected by the fifth surface205, totally reflected by the sixth surface 206, refracted by the fifthsurface 205, and forms an image on an imaging plane 45.

An eccentric prism 210 of the prism unit 30 b shown in FIG. 79 has afirst surface 211, second surface 212, and third surface 213 all ofwhich are formed from free-form surfaces. Light input through anaperture member 214 is refracted by the first surface 211 and enters theeccentric prism 210. The light is internally reflected by the secondsurface 212, strikes the first surface 211 again and is totallyreflected by it. The light is then internally reflected by the thirdsurface 213, totally reflected by the first surface 211 again,internally reflected by the third surface 213 again, refracted by thefirst surface 211 again, and forms an image on an imaging plane 45.

In the prism unit 30 c shown in FIG. 80, all surfaces 231 to 238 of afirst prism 221 and second prism 222 are formed from free-form surfaces.Light input from the first surface 231 is refracted by it and totallyreflected by the second surface 232. The light is then totally reflectedby the third surface 233 and refracted by the fourth surface 234 andfifth surface 235. The light is further totally reflected by the sixthsurface 236 and seventh surface 237, refracted by the eighth surface238, and forms an image on an imaging plane 45.

FIG. 81 shows the outer appearance of a digital camera 1 a whichcomprises only a fine adjustment mechanism or adjustment mechanism andno manual operation switching member. FIG. 82 is a sectional viewschematically showing the internal structure of the digital camera 1 a.A cellular phone 160 a with a camera shown in FIG. 83 incorporates animage sensing device (e.g., the image sensing device 10 b, 10 c, or 10k) having only a fine adjustment mechanism or adjustment mechanism or animage sensing device whose switching mechanism is operated by anactuator.

FIGS. 84 to 86 schematically show examples in which the prism opticalsystems shown in FIGS. 79 to 81 are applied to an image sensing devicewhich comprises a fine adjustment mechanism or adjustment mechanism andcan execute fc adjustment.

In practicing the present invention, various changes and modificationscan be made for the constituent elements such as the prism opticalsystem, guide mechanism, image sensing element, and switching mechanismwithout departing from the spirit and scope of the present invention.

The image sensing device having a switching mechanism can selectivelyswitch the position of the prism unit between the first image sensingposition and the second image sensing position in the directionperpendicular to the light-receiving surface of the image sensingelement. Hence, two focal points can be set in the distance from thelight-receiving surface of the image sensing element to an object.

According to the image sensing device having a link mechanism, the prismunit can be switched between the first position near the image sensingelement and the second position separated from the image sensingelement. At this time, the prism unit moves along the directionperpendicular to the light-receiving surface of the image sensingelement while keeping its posture parallel. In the image sensing device,two different focal points can be set in accordance with the imagesensing distance of an object. Hence, image sensing can be executed byselecting these two image sensing settings.

The prism unit can be switched between the first position and the secondposition in the direction perpendicular to the light-receiving surfaceof the image sensing element. For this reason, image sensing can beexecuted in accordance with two image sensing states, i.e., a case inwhich the position of an object to be sensed falls within the firstdistance range and a case in which the object position falls within thesecond distance range. In addition, since the switching mechanism can beimplemented in a small space, the image sensing device and an imagesensing apparatus incorporating it can be made compact.

According to the image sensing device of the present invention, whichcomprises a fine adjustment mechanism or adjustment mechanism,variations between products caused by manufacturing dimensionaltolerances or assembly dimensional tolerances in mass production canindividually be corrected. Even when the distance from the prism unit tothe light-receiving surface of the image sensing element changes due tovariations in dimensions of each component of the image sensing deviceor a variation in assembly, the focal plane can be adjusted. For thisreason, the image sensing device of the present invention can maintain asatisfactory focus state even in, e.g., mass production.

In the image sensing device in which a rotational support portionpivotally supporting the prism unit is arranged in parallel to thelight-receiving surface of the image sensing element, the distancebetween the prism unit and the light-receiving surface of the imagesensing element is changed in the direction along the exit optical axisof the prism unit within the rotational range of the pivot supportportion. Since the prism unit pivots by using the pivot support portionas a fulcrum, the adjustment mechanism can be formed by a small numberof components.

In practicing the present invention, various changes and modificationscan be made for the constituent elements such as the prism opticalsystem, image sensing element, adjustment member, and receiving portionwithout departing from the spirit and scope of the present invention.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. An image sensing device comprising: a prism unit which receives alight beam from an object and forms an object image on an imaging plane,the prism unit having at least two reflecting surfaces each having afree-form surface shape, and an incident optical axis of the light beaminput from the object and an exit optical axis of the light beam whichexits from the prism unit to the imaging plane being arrangedsubstantially in parallel at a predetermined interval; an image sensingelement which is arranged on the imaging plane to convert the objectimage formed by the prism unit into an electrical signal; an adjustmentmember which can move in a plane parallel to the light-receiving surfaceof the image sensing element to finely adjust a position of the prismunit in a direction perpendicular to the light-receiving surface of theimage sensing element; and a receiving portion which is arranged on theprism unit and abuts against the adjustment member to finely adjust theposition of the prism unit in the direction perpendicular to thelight-receiving surface.
 2. An image sensing apparatus comprising: aprism unit which receives a light beam from an object and forms anobject image on an imaging plane, the prism unit having at least tworeflecting surfaces each having a free-form surface shape, and anincident optical axis of the light beam input from the object and anexit optical axis of the light beam which exits from the prism unit tothe imaging plane being arranged substantially in parallel at apredetermined interval; an image sensing element which is arranged onthe imaging plane to convert the object image formed by the prism unitinto an electrical signal; an adjustment member which can move in aplane parallel to the light-receiving surface of the image sensingelement to finely adjust a position of the prism unit in a directionperpendicular to the light-receiving surface of the image sensingelement; a receiving portion which is arranged on the prism unit andabuts against the adjustment member to finely adjust the position of theprism unit in the direction perpendicular to the light-receivingsurface; processing means for executing predetermined electricalprocessing for the electrical signal obtained by the image sensingelement to obtain image data; and recording means for recording theimage data from the processing means on an applied information recordingmedium.
 3. A device according to claim 1, wherein the prism unitcomprises two prisms and an aperture member arranged between the prisms;said two prisms each including at least one reflecting surface having afree-form surface shape, a light incident surface having a refractingpower, and a light exit surface having a refracting power, and anaperture member arranged between the prisms.
 4. A device according toclaim 1, wherein the adjustment member can rotate in the plane parallelto the light-receiving surface of the image sensing element.
 5. A deviceaccording to claim 1, wherein the adjustment member has, at a portionwhich abuts against the receiving portion, a slant whose position in adirection perpendicular to the light-receiving surface of the imagesensing element changes along a direction in which the adjustment membermoves.
 6. A device according to claim 5, wherein the receiving portioncomprises an incline having a shape conforming to the slant of theadjustment member at a portion which abuts against the slant of theadjustment member.
 7. A device according to claim 1, further comprisinga fixing portion to fix the adjustment member at a predeterminedposition.
 8. A device according to claim 1, wherein the adjustmentmember comprises an eccentric cam to finely adjust a position of theadjustment member.
 9. A device according to claim 1, wherein theadjustment member comprises an eccentric pin to finely adjust a positionof the adjustment member.
 10. A device according to claim 1, wherein theadjustment member has a first portion against which the receivingportion of the prism unit abuts, and a second portion which comes intocontact with an fc adjustment jig to move the adjustment member in adirection parallel to the light-receiving surface of the image sensingelement and is separated from the first portion in a state in which thefirst portion is fixed at a predetermined position with respect to theprism unit.
 11. A method of manufacturing an image sensing device whichincludes a prism unit which receives a light beam from an object andforms an object image on an imaging plane, the prism unit having atleast two reflecting surfaces each having a free-form surface shape, andan incident optical axis of the light beam input from the object and anexit optical axis of the light beam which exits from the prism unit tothe imaging plane being arranged substantially in parallel at apredetermined interval, an image sensing element which is arranged onthe imaging plane to convert the object image formed by the prism unitinto an electrical signal; an adjustment mechanism for finely adjustinga position of the prism unit in a direction perpendicular to thelight-receiving surface of the image sensing element said adjustmentmechanism including: an adjustment member which can move in a planeparallel to the light-receiving surface of the image sensing element;and a receiving portion which is arranged on the prism unit and abutsagainst the adjustment member to finely adjust the position of the prismunit in the direction perpendicular to the light-receiving surface, saidadjustment member having a first portion against which the receivingportion of the prism unit abuts, and a second portion which comes intocontact with an fc adjustment jig to move the adjustment member in theplane parallel to the light-receiving surface of the image sensingelement, the method of manufacturing comprising steps of: assembling theprism unit, the image sensing element, and the adjustment mechanism;fixing the first portion of the adjustment member; and separating thesecond portion of the adjustment member.
 12. A method of adjusting animage sensing device which includes a prism unit which receives a lightbeam from an object and forms an object image on an imaging plane, theprism unit having at least two reflecting surfaces each having afree-form surface shape, and an incident optical axis of the light beaminput from the object and an exit optical axis of the light beam whichexits from the prism unit-to the imaging plane being arrangedsubstantially in parallel at a predetermined interval, an image sensingelement which is arranged on the imaging plane to convert the objectimage formed by the prism unit into an electrical signal, an adjustmentmember which can move in a plane parallel to the light-receiving surfaceof the image sensing element to finely adjust a position of the prismunit in a direction perpendicular to the light-receiving surface of theimage sensing element, and a receiving portion which is arranged on theprism unit and abuts against the adjustment member to finely adjust theposition of the prism unit in the direction perpendicular to thelight-receiving surface; the method comprising: executing fineadjustment by moving the adjustment member in the plane parallel to thelight-receiving surface of the image sensing element; and fixing theadjustment member.
 13. An image sensing device comprising: an opticalsystem which receives a light beam from an object and forms an objectimage on an imaging plane, the optical system having at least tworeflecting surfaces each having a free-form surface shape, and anincident optical axis of the light beam input from the object and anexit optical axis of the light beam which exits from the optical systemto the imaging plane being arranged substantially in parallel at apredetermined interval; an image sensing element which is arranged onthe imaging plane to convert the object image formed by the opticalsystem into an electrical signal; adjustment means which moves in aplane parallel to the light-receiving surface of the image sensingelement to finely adjust a position of the optical system in a directionperpendicular to the light-receiving surface of the image sensingelement; and receiving means, arranged on the optical system andsynchronized with the adjustment means, for finely adjusting theposition of the optical system in the direction perpendicular to thelight-receiving surface.